Fix commutation DAG linting

[antalszava]

Fixes the following issues with linting:

[github-actions]

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[codecov]

Codecov Report

Merging #2258 (8d49204) into master (b494a2b) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #2258   +/-   ##
=======================================
  Coverage   99.27%   99.27%           
=======================================
  Files         232      232           
  Lines       18708    18712    +4     
=======================================
+ Hits        18573    18577    +4     
  Misses        135      135           

Impacted Files	Coverage Δ
pennylane/transforms/commutation_dag.py	99.68% <100.00%> (+<0.01%)	⬆️

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[dime10]

Looks good 👍