DM-45209: Fix E721 linter warning

[timj]

Checklist

• ran Jenkins
• added a release note for user-visible changes to doc/changes
• (if changing dimensions.yaml) make a copy of dimensions.yaml in configs/old_dimensions

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 89.36%. Comparing base (11c1998) to head (6a90377).

Files	Patch %	Lines
python/lsst/daf/butler/dimensions/_records.py	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1037   +/-   ##
=======================================
  Coverage   89.36%   89.36%           
=======================================
  Files         359      359           
  Lines       45511    45511           
  Branches     9354     9354           
=======================================
  Hits        40673    40673           
  Misses       3536     3536           
  Partials     1302     1302           

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