Drop support for Python 3.8

[irtazaakram]

End support for Python 3.8 as it reaches its end of life (EOL), and Open edX now supports Python 3.11.

Reference PR: https://github.com/openedx/event-bus-redis/pull/113/files

• update setup.py, pyproject.toml, tox.ini, or any other configuration files that specify Python 3.8
• remove Python 3.8 from the test matrix in CI configurations
• update dependencies to ensure compatibility with Python 3.11+
• update README, installation guides, and other documentation to reflect python 3.11 instead of python 3.8
• add a note in the release changelog about the removal of Python 3.8 support
• Update the major version so we could release it after the merging of PR
• Test Cases should be passed before pushing PR for code review

[irtazaakram]

Resolved by #244