Fix benchmarks link in PR checklist

[trexfeathers]

Description

Was previously using .. relative notation, but visiting a file in GitHub actually requires a blob URL.

Checklist

Important

The Iris core developers are here to help! If anything below is unclear, just post a comment asking for help 😊

• Included a What's New entry
• Incorporated type hints in any changed code
• Checked if tests need updating
• Checked if benchmarks need updating
• Checked if documentation needs updating
  • Docstrings (we love code examples!)
  • User Manual pages
• Checked if dependencies need updating
• Confirmed that the GitHub 'checks' on this PR are passing ✅
  (further reading)

---

Tip

Things you can trigger on this PR:

• Add this label to trigger benchmarks: benchmark_this Request that this pull request be benchmarked to check if it introduces performance shifts
• Visit this URL - swapping 9999 for this PR's number - to re-trigger the CLA check:
  https://cla-assistant.io/check/SciTools/iris?pullRequest=9999

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.15%. Comparing base (2ad53e9) to head (47d9488).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7164   +/-   ##
=======================================
  Coverage   90.15%   90.15%           
=======================================
  Files          91       91           
  Lines       24983    24983           
  Branches     4685     4685           
=======================================
  Hits        22524    22524           
  Misses       1682     1682           
  Partials      777      777           

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[pp-mo]

I'm puzzled.
The link as-is does work, Sphinx allows relative paths, why do we not want them?
Plus, the links are all to "latest" which seems slightly unwise anyway : don't we want each docs version to be self-complete ?

[trexfeathers]

@pp-mo

The link as-is does work

It only works if you're viewing the template file. If you're viewing the checklist within an actual pull request, it doesn't work. This is how I missed it in the first place.

the links are all to "latest" which seems slightly unwise anyway

That's important in this case, since developer guidelines can change between releases. Examples:

• We have significantly changed the What's New guidance today
• The last couple of years have involved big modifications to testing guidelines (mainly PyTest)

... in both cases, following the guidance in the stable documentation would have meant doing it wrong.

[pp-mo]

OK I get it now!