Fix pre-commit isort failure on pytorch_lightning/accelerators

[arnaudgelas]

What does this PR do?

Relates to #4805work-on-github/linking-a-pull-request-to-an-issue#linking-a-pull-request-to-an-issue-using-a-keyword)

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[codecov]

Codecov Report

Merging #5503 (9faeaf6) into release/1.2-dev (2fe36c7) will decrease coverage by 0%.
The diff coverage is 100%.

@@               Coverage Diff               @@
##           release/1.2-dev   #5503   +/-   ##
===============================================
- Coverage               93%     93%   -0%     
===============================================
  Files                  152     152           
  Lines                10736   10735    -1     
===============================================
- Hits                  9948    9947    -1     
  Misses                 788     788