use upload-artifact@v4 (#812)

### Description
GitHub is disabling older versions of this action. See
https://github.com/actions/upload-artifact?tab=readme-ov-file#actionsupload-artifact.

### Related issues
N/A

### Checklist
_Before this pull request can be reviewed, all of these tasks should be
completed. Denote completed tasks with an `x` inside the square brackets
`[ ]` in the Markdown source below:_
- [x] I have added a description (see above).
- [x] I have added a link to any related issues (if applicable; see
above).
- [x] I have read the [Contributing
Guide](https://github.com/quokka-astro/quokka/blob/development/CONTRIBUTING.md).
- [ ] I have added tests for any new physics that this PR adds to the
code.
- [ ] *(For quokka-astro org members)* I have manually triggered the GPU
tests with the magic comment `/azp run`.

.github/workflows/docs.yml

@@ -56,7 +56,7 @@ jobs:
           INPUT_PATH: ./docs/site
 
       - name: Upload artifact
-        uses: actions/upload-artifact@main
+        uses: actions/upload-artifact@v4
         with:
           name: 'github-pages'
           path: ${{ runner.temp }}/artifact.tar

.github/workflows/scorecard.yml

@@ -59,7 +59,7 @@ jobs:
       # Upload the results as artifacts (optional). Commenting out will disable uploads of run results in SARIF
       # format to the repository Actions tab.
       - name: "Upload artifact"
-        uses: actions/upload-artifact@97a0fba1372883ab732affbe8f94b823f91727db # v3.pre.node20
+        uses: actions/upload-artifact@184d73b71b93c222403b2e7f1ffebe4508014249 # v4
         with:
           name: SARIF file
           path: results.sarif