numpy 2.0 removal

[ericpre]

Use ruff check . --select NPY201 to find these.

For reference: https://numpy.org/devdocs/release/2.0.0-notes.html#numpy-2-0-python-api-removals.

Progress of the PR

• Replace deprecated np.string_ by np.bytes_,
• [n/a] update docstring (if appropriate),
• [n/a] update user guide (if appropriate),
• add an changelog entry in the upcoming_changes folder (see upcoming_changes/README.rst),
• Check formatting changelog entry in the readthedocs doc build of this PR (link in github checks)
• [n/a] add tests,
• ready for review.

[codecov]

Codecov Report

Attention: Patch coverage is 25.00000% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 80.51%. Comparing base (ccba4ff) to head (8192377).

Files	Patch %	Lines
hyperspy/model.py	0.00%	0 Missing and 2 partials ⚠️
hyperspy/misc/utils.py	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@                 Coverage Diff                 @@
##           RELEASE_next_patch    #3338   +/-   ##
===================================================
  Coverage               80.51%   80.51%           
===================================================
  Files                     147      147           
  Lines                   21869    21869           
  Branches                 5146     5146           
===================================================
  Hits                    17607    17607           
  Misses                   3044     3044           
  Partials                 1218     1218           

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