dim/models: replace deprecated pkg_resources

[zeromind]

replace deprecated pkg_resources with importlib.resources according to the migration guide

https://importlib-resources.readthedocs.io/en/latest/migration.html

resolves deprecation warning:

# /opt/dim/bin/manage_dim --help
/opt/dim/lib64/python3.9/site-packages/dim/models/migrate.py:7: UserWarning: pkg_resources is deprecated as an API. See https://setuptools.pypa.io/en/latest/pkg_resources.html. The pkg_resources package is slated for removal as early as 2025-11-30. Refrain from using this package or pin to Setuptools<81.
  import pkg_resources

[miesi-ionos]

Cool, please merge.