Fix missing 'packaging' requirement

[mattoberle]

Description

The sqlalchemy instrumentation uses the packaging library to parse the sqlalchemy SemVer.

packaging is not part of the standard library and should be included in the setup.cfg file to avoid:

ModuleNotFoundError: No module named 'packaging'

Note: I chose the latest version of packaging because the supported python versions align with those of the sqlalchemy instrumentation, but open to alternatives.

A different approach would be to just remove the extra requirement.
Since we are just checking for >=1.4 (and don't care about all the extra SemVer stuff):

if tuple(map(int, sqlalchemy.__version__.split('.')[:2])) >= (1, 4):
    ...

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Does This PR Require a Core Repo Change?

• No.

Checklist:

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

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