[ci] Bump actions/setup-python to v5.1.1 (#282)

### Summary

See #260 for background.

Update the
[`actions/setup-python`](https://github.com/actions/setup-python) action
to the most recent version:
[v5.1.1](https://github.com/actions/setup-python/releases/tag/v5.1.1).
Quick summary of major versions:
* [v4](https://github.com/actions/setup-python/releases/tag/v4.0.0):
there is no longer a default `python-version` set in the Action, so
implementers must specify one. We already specify one, so we should be
ok.
* [v5](https://github.com/actions/setup-python/releases/tag/v5.0.0)
contained the Node20 upgrade

### Test Plan
- [X] Verify [new
hash](https://github.com/aurora-opensource/au/actions/runs/10254719343/job/28370096506#step:4:1)
on this PR
- [X] Checked job summary and saw no deprecation warnings related to
`actions/setup-python`
- [X] Checked the changelog and didn't see any backwards incompatible
changes

Co-authored-by: Chip Hogg <[email protected]>

.github/workflows/single-file-build-and-test.yml

@@ -32,7 +32,7 @@ jobs:
         uses: ilammy/msvc-dev-cmd@0b201ec74fa43914dc39ae48a89fd1d8cb592756 #v1.13.0
 
       - name: Set up python
-        uses: actions/setup-python@3542bca2639a428e1796aaa6a2ffef0c0f575566 #v3.1.4
+        uses: actions/setup-python@39cd14951b08e74b54015e9e001cdefcf80e669f #v5.1.1
         with:
           python-version: '3.10'