MNT: replace deprecated pkg_resources with importlib.metadata.distributions

[tangkong]

Description

• pkg_resources was fully deprecated in setuptools 82, and builds are starting to pick this up
• importlib.metadata has existed since py3.8 apparently

Motivation and Context

pcds-envs had hutch-python fail here recently.

How Has This Been Tested?

pytest, and opening hutch-python in --debug mode to see that there's still sensible env dump information

Where Has This Been Documented?

This PR

Pre-merge checklist

• Code works interactively (a real hutch config file can be loaded)
• Code contains descriptive docstrings, including context and API
• New/changed functions and methods are covered in the test suite where possible
• Test suite passes locally
• Test suite passes on GitHub Actions
• Ran docs/pre-release-notes.sh and created a pre-release documentation page
• Pre-release docs include context, functional descriptions, and contributors as appropriate

[tangkong]

The conda test has setuptools 82, which was the version that fully removed pkg_resources

[ZLLentz]

This is a reasonable fix