Drop support for Python 3.8 and disable tests broken in 8.1.0..8.1.1

[mkmkme]

Some of MONITOR tests got broken due to a bug in the server: valkey-io/valkey#2036

This commit disables those tests for these versions of Valkey server thus letting the CI proceed.

Pull Request check-list

• Do tests and lints pass with this change?
• Do the CI tests pass with this change (enable it first in your forked repo and wait for the github action build to finish)?
• Is the new or changed code fully tested?
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?
• Is there an example added to the examples folder (if applicable)?

Description of change

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.17%. Comparing base (994ed74) to head (be835c3).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #193      +/-   ##
==========================================
- Coverage   76.25%   76.17%   -0.09%     
==========================================
  Files         130      130              
  Lines       33970    33980      +10     
==========================================
- Hits        25904    25883      -21     
- Misses       8066     8097      +31     

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[bogdanp05]

lgtm