Support test with redis unstable docker

[dvora-h]

Pull Request check-list

Please make sure to review and check all of these items:

• Does $ tox pass with this change (including linting)?
• 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)?

NOTE: these things are not required to open a PR and can be done
afterwards / while the PR is open.

Description of change

Please provide a description of the change here.

[codecov-commenter]

Codecov Report

Merging #1850 (69c59bf) into master (231d402) will decrease coverage by 0.04%.
The diff coverage is 57.14%.

@@            Coverage Diff             @@
##           master    #1850      +/-   ##
==========================================
- Coverage   93.64%   93.60%   -0.05%     
==========================================
  Files          76       76              
  Lines       16207    16214       +7     
==========================================
  Hits        15177    15177              
- Misses       1030     1037       +7     

Impacted Files	Coverage Δ
tests/conftest.py	89.63% <57.14%> (-1.06%)	⬇️
tests/test_search.py	98.78% <0.00%> (-0.25%)	⬇️
tests/test_cluster.py	98.66% <0.00%> (-0.13%)	⬇️

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