Fix ruff complaint about c-style formatting

[dhirving]

The new version of ruff no longer allows '%' formatting, instead requiring the use of f-strings.

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

[timj]

Looks like v0.4.2 of ruff enhanced the UP031 rule detection: astral-sh/ruff#11019

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.04%. Comparing base (ecffc00) to head (585f067).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1004   +/-   ##
=======================================
  Coverage   89.04%   89.04%           
=======================================
  Files         347      347           
  Lines       44473    44473           
  Branches     9146     9146           
=======================================
  Hits        39601    39601           
  Misses       3550     3550           
  Partials     1322     1322           

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