Fix AttributeError when trying to split library version

[SessionIssue]

Fallback for issue #2215

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)?
• Was the change added to CHANGES file?

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.

Fallback for splitting version NoneType

[codecov-commenter]

Codecov Report

Base: 92.23% // Head: 92.20% // Decreases project coverage by -0.02% ⚠️

Coverage data is based on head (292c3a6) compared to base (ed38e77).
Patch coverage: 50.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2539      +/-   ##
==========================================
- Coverage   92.23%   92.20%   -0.03%     
==========================================
  Files         113      113              
  Lines       29388    29391       +3     
==========================================
- Hits        27106    27101       -5     
- Misses       2282     2290       +8     

Impacted Files	Coverage Δ
redis/__init__.py	76.92% <50.00%> (-5.69%)	⬇️
tests/test_asyncio/test_search.py	98.29% <0.00%> (-0.35%)	⬇️
tests/test_asyncio/test_cluster.py	97.48% <0.00%> (-0.13%)	⬇️
tests/test_cluster.py	96.90% <0.00%> (-0.12%)	⬇️

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