Remove references to Python 3.7

[ptitzler]

This PR updates references to Python v3.7, which is no longer supported by Jupyterlab 4.0. To locate impacted files I've scanned the repository for 3.7 and 37.

Need input on https://github.com/ptitzler/elyra/blob/rip-py7/pyproject.toml#L23 (What's supposed to be the new floor?)

Signed-off-by: Patrick Titzler ptitzler@us.ibm.com

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[kevin-bates]

Need input on https://github.com/ptitzler/elyra/blob/rip-py7/pyproject.toml#L23 (What's supposed to be the new floor?)

There's no need to increase the floor as newer versions of Python work fine. That comment was there to prevent its increase so long as Python 3.7 was supported - otherwise 3.7 installations would break. Since this is removing its support, we should remove the comment.

[kevin-bates]

Wow - we really had to introduce lots of one-offs for 3.7 - this winds up being a nice cleanup - thanks.

Just a couple nits on tightening up the classifiers.

[kevin-bates]

LGTM - thanks @ptitzler.