misc: use stdlib "importlib.metadata" on Python >= 3.12

[herin049]

Description

Switches to using the standard library's importlib.metadata module for Python versions 3.12 and above, eliminating the importlib_metadata dependency for Python 3.12 and above.

Type of change

Please delete options that are not relevant.

• 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?

uv run tox -e py314-test-opentelemetry-sdk
uv run tox -e py310-test-opentelemetry-sdk

Does This PR Require a Contrib Repo Change?

• Yes. - Link to PR:
• No.

Checklist:

• Followed the style guidelines of this project
• Changelogs have been updated
• Documentation has been updated

[xrmx]

We discussed this when we introduced the shim module and we decided for having the same library instead of having per python version behavior. It was a different time and now we support more version with stdlib support than not but I guess a topic for next SIG call?