NumPy2 support fix

[alexmgoldberg]

Issue Number. Is this pull request related to any outstanding issues? If so, list the issue number.
Fixes #372

Describe the changes made. A clear and concise description of what the problem is and what you did to fix it. E.g. [...] was happening and I've changed [...] to fix it.
Ran ruff to support numpy2
There are no instances of NPY201 errors found 7 instances of NPY201 errors found, easily fixed.
There are unrelated unfixed errors below:

ruff check .
src/westpa/__init__.py:16:1: E402 Module level import not at top of file
src/westpa/cli/tools/w_assign.py:477:23: NPY201 [*] `np.string_` will be removed in NumPy 2.0. Use `numpy.bytes_` instead.
src/westpa/cli/tools/w_assign.py:484:33: NPY201 [*] `np.string_` will be removed in NumPy 2.0. Use `numpy.bytes_` instead.
src/westpa/cli/tools/w_assign.py:487:52: NPY201 [*] `np.string_` will be removed in NumPy 2.0. Use `numpy.bytes_` instead.
src/westpa/cli/tools/w_assign.py:561:39: NPY201 [*] `np.string_` will be removed in NumPy 2.0. Use `numpy.bytes_` instead.
src/westpa/cli/tools/w_eddist.py:493:20: F841 Local variable `n_iter` is assigned to but never used
src/westpa/cli/tools/w_ipa.py:163:29: E741 Ambiguous variable name: `l`
src/westpa/cli/tools/w_multi_west.py:6:1: E402 Module level import not at top of file
src/westpa/cli/tools/w_multi_west.py:7:1: E402 Module level import not at top of file
src/westpa/cli/tools/w_multi_west.py:8:1: E402 Module level import not at top of file
src/westpa/cli/tools/w_multi_west.py:9:1: E402 Module level import not at top of file
src/westpa/cli/tools/w_multi_west.py:10:1: E402 Module level import not at top of file
src/westpa/cli/tools/w_multi_west.py:13:1: E402 Module level import not at top of file
src/westpa/cli/tools/w_pdist.py:496:20: F841 Local variable `n_iter` is assigned to but never used
src/westpa/cli/tools/w_red.py:226:20: F841 Local variable `cilb` is assigned to but never used
src/westpa/cli/tools/w_red.py:226:26: F841 Local variable `ciub` is assigned to but never used
src/westpa/core/_rc.py:46:16: E721 Use `is` and `is not` for type comparisons, or `isinstance()` for isinstance checks
src/westpa/core/binning/mab.py:70:9: F841 Local variable `eigval` is assigned to but never used
src/westpa/core/h5io.py:345:47: NPY201 [*] `np.string_` will be removed in NumPy 2.0. Use `numpy.bytes_` instead.
src/westpa/core/h5io.py:348:50: NPY201 [*] `np.string_` will be removed in NumPy 2.0. Use `numpy.bytes_` instead.
src/westpa/core/propagators/executable.py:625:13: F841 Local variable `rusage` is assigned to but never used
src/westpa/core/propagators/executable.py:634:13: F841 Local variable `rusage` is assigned to but never used
src/westpa/core/propagators/executable.py:654:21: F841 Local variable `rusage` is assigned to but never used
src/westpa/core/propagators/executable.py:665:21: F841 Local variable `rusage` is assigned to but never used
src/westpa/core/sim_manager.py:347:17: F841 Local variable `rbstate` is assigned to but never used
src/westpa/core/we_driver.py:550:26: F841 Local variable `parent` is assigned to but never used
src/westpa/core/we_driver.py:591:37: F841 Local variable `parent` is assigned to but never used
src/westpa/core/we_driver.py:614:26: F841 Local variable `parent` is assigned to but never used
src/westpa/core/we_driver.py:679:35: F841 Local variable `parent` is assigned to but never used
src/westpa/oldtools/aframe/trajwalker.py:5:1: E402 Module level import not at top of file
src/westpa/westext/hamsm_restarting/example_overrides.py:10:1: E402 Module level import not at top of file
src/westpa/westext/stringmethod/string_method.py:179:33: NPY201 [*] `np.mat` will be removed in NumPy 2.0. Use `numpy.asmatrix` instead.
src/westpa/westext/stringmethod/string_method.py:244:17: E731 Do not assign a `lambda` expression, use a `def`
src/westpa/work_managers/zeromq/node.py:12:1: E402 Module level import not at top of file
src/westpa/work_managers/zeromq/node.py:14:1: E402 Module level import not at top of file
src/westpa/work_managers/zeromq/node.py:15:1: E402 Module level import not at top of file
src/westpa/work_managers/zeromq/work_manager.py:397:13: F841 Local variable `task_id` is assigned to but never used
tests/test_binning.py:54:9: E731 Do not assign a `lambda` expression, use a `def`
tests/test_binning.py:55:9: E731 Do not assign a `lambda` expression, use a `def`
tests/test_functional/test_mclib.py:43:40: F841 Local variable `k_` is assigned to but never used
tests/test_tools/test_w_states.py:18:14: F841 Local variable `err` is assigned to but never used
Found 41 errors.
[*] 7 fixable with the `--fix` option (19 hidden fixes can be enabled with the `--unsafe-fixes` option).

All tests passed when numpy commit 539dafa was installed

Goals and Outstanding Issues. A clear and concise list of goals (to be) accomplished.

• Make sure numpy2 is supported
• Fixed additional ruff lint errors

Major files changed.

• see below

Status.

• Bug fix (non-breaking change which fixes an issue)
• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• All new and existing tests passed.

Additional context. Add any other context or screenshots about the pull request here.

[codecov]

Codecov Report

Attention: 4 lines in your changes are missing coverage. Please review.

Comparison is base (1fd4f8a) 41.92% compared to head (80aae91) 41.92%.

Files	Patch %	Lines
src/westpa/core/data_manager.py	0.00%	2 Missing ⚠️
src/westpa/core/h5io.py	50.00%	1 Missing ⚠️
src/westpa/westext/stringmethod/string_method.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #374   +/-   ##
========================================
  Coverage    41.92%   41.92%           
========================================
  Files          131      131           
  Lines        17009    17009           
========================================
  Hits          7131     7131           
  Misses        9878     9878           

Flag	Coverage Δ
unittests	41.92% <60.00%> (ø)

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[jeremyleung521]

LGTM after those new commits. However, we might actually hold this until the numpy 2.0 release candidate is released (Feb 1st, 2024 Week 2 or 3 of Feb ???) as more breaking changes might arise (as per this thread).