Drop Python 3.8 & Add Support for Python 3.12

[irtazaakram]

Description:

Follow and complete all of the following steps for the issue to be marked as done.

• Update the tox.ini, setup.py, setup.cfg, or pyproject.toml to remove Python 3.8 and add support for Python 3.12.
• Ensure GitHub Actions workflows, including the CI matrix, are updated to reflect the supported Python versions (3.11, and 3.12).
• Adjust any testing or build configurations to ensure compatibility with Python 3.12.
• Remove references to Python versions earlier than 3.11 from all relevant configuration files.
• Run all tests and verify they pass in the CI with the updated versions.
• Add a CHANGELOG entry: “Dropped support for Python 3.8 and added support for Python 3.12.”
• Bump the package version and release a new version on GitHub & PyPI (where applicable).

[iamsobanjaved]

@feanil do we want to run both 3.11 and 3.12 tests in parallel in edx-platform on github actions?

[feanil]

Previously we ran both in paralllel for a short period of time (2 weeks) and only ran a minimal number of tests on the old version until the next named release was cut. I think we should follow the same plan this time as long as we don't find that operators would have to make major changes to switch from python 3.11 to 3.12.