Using importlib_metadata for entry points instead of pkg_resources

[jeremydvoss]

Description

pkg_resources is deprecated. Following example of https://github.com/open-telemetry/opentelemetry-python/pull/3217/files

Helps to fix #1970

Type of change

Please delete options that are not relevant.

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

How Has This Been Tested?

Existing tests

Does This PR Require a Core Repo Change?

• [ ] Yes. - Link to PR:
• [x] No.

Checklist:

See contributing.md for styleguide, changelog guidelines, and more.

• [x] Followed the style guidelines of this project
• [x] Changelogs have been updated
• [ ] Unit tests have been added
• [ ] Documentation has been updated