Update rstest dev-dependency from 0.23 to 0.26

[musicinmybrain]

I don’t see any changes that should affect this project between these two versions (https://github.com/la10736/rstest/blob/v0.26.1/CHANGELOG.md), and I confirmed that cargo test -p time --all-features still passes.

(I’m patching the dev-dependency in Fedora’s rust-time package to remove one of the dependencies on our rust-rstest0.23 compat package so we don’t have to maintain it indefinitely, and it’s our policy to offer patches upstream. See #716 for more discussion on motivation, although this PR should be more straightforward since it doesn’t affect MSRV.)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.7%. Comparing base (53b0941) to head (68220d5).

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #747   +/-   ##
=====================================
  Coverage   92.7%   92.7%           
=====================================
  Files         96      96           
  Lines       9772    9772           
=====================================
  Hits        9060    9060           
  Misses       712     712           

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