Use https://github.com/MetOffice/mule instead of old location

[trexfeathers]

🚀 Pull Request

Description

Closes #6856

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• benchmark_this Request that this pull request be benchmarked to check if it introduces performance shifts

[scitools-ci]

• Please see: SciTools/.github#242

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.43%. Comparing base (ace09fc) to head (02346a9).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6879   +/-   ##
=======================================
  Coverage   90.43%   90.43%           
=======================================
  Files          91       91           
  Lines       24839    24839           
  Branches     4656     4656           
=======================================
  Hits        22463    22463           
  Misses       1608     1608           
  Partials      768      768           

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[ukmo-ccbunney]

All looking fine.
Good to remove that monkey patch 👍🏼
LGTM.

Templated file adjusted appropriately in SciTools/.github#243

[trexfeathers]

Thanks @ukmo-ccbunney!