fix: add missing packaging dependency

[zeke]

This PR is an attempt to fix a ModuleNotFoundError when importing the replicate library by adding the missing packaging dependency to pyproject.toml.

Not sure if this is the right way to add this dep. @dgellow I could use your guidance here!

Problem

The replicate.lib._schema module imports packaging.version but the packaging library wasn't declared as a dependency, causing runtime errors:

ModuleNotFoundError: No module named 'packaging'

Original error

Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File "/usr/local/lib/python3.13/site-packages/coglet/schema.py", line 53, in <module>
    main()
    ~~~~^^
  File "/usr/local/lib/python3.13/site-packages/coglet/schema.py", line 44, in main
    raise e
  File "/usr/local/lib/python3.13/site-packages/coglet/schema.py", line 31, in main
    p = inspector.create_predictor(sys.argv[1], sys.argv[2], inspect_ast=True)
  File "/usr/local/lib/python3.13/site-packages/coglet/inspector.py", line 356, in create_predictor
    module = importlib.import_module(module_name)
  File "/usr/local/lib/python3.13/importlib/__init__.py", line 88, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1387, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1360, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1331, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 935, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 1026, in exec_module
  File "<frozen importlib._bootstrap>", line 488, in _call_with_frames_removed
  File "/src/main.py", line 5, in <module>
    import replicate
  File "/usr/local/lib/python3.13/site-packages/replicate/__init__.py", line 11, in <module>
    from ._client import (
    ...<9 lines>...
    )
  File "/usr/local/lib/python3.13/site-packages/replicate/_client.py", line 25, in <module>
    from replicate.lib._predictions_run import Model, Version, ModelVersionIdentifier
  File "/usr/local/lib/python3.13/site-packages/replicate/lib/_predictions_run.py", line 9, in <module>
    from replicate.lib._schema import make_schema_backwards_compatible
  File "/usr/local/lib/python3.13/site-packages/replicate/lib/_schema.py", line 3, in <module>
    from packaging import version
ModuleNotFoundError: No module named 'packaging'

[dgellow]

LGTM!

I would recommend to run uv sync locally to update the uv.lock lockfile before merging