AIP-9471 - Remove pkg_resources

[cavandervoort]

Remove pkg_resources because it is deprecated and is causing issues.

I confirmed that the lines of code/functions that formerly had import pkg_resources in metaflow/metaflow_config.py and metaflow/__init__.py are being reached, and that they are no longer causing the pkg_resources warning.

See this workflow's output, which contains since-deleted print statements:

BEFORE metaflow_config.py: from importlib.metadata import version
AFTER metaflow_config.py: from importlib.metadata import version
BEFORE metaflow_config.py: from importlib.metadata import version
AFTER metaflow_config.py: from importlib.metadata import version
BEFORE __init__.py: from importlib.metadata import version
AFTER __init__.py: from importlib.metadata import version
BEFORE __init__.py: from importlib.metadata import version
AFTER __init__.py: from importlib.metadata import version

I also tested the latest version of metaflow in this commit to the synthetic tests.