build(deps): Bump actions/upload-artifact from 3 to 4

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 3 to 4.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v3...v4)

---
updated-dependencies:
- dependency-name: actions/upload-artifact
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/ci.yml

@@ -49,7 +49,7 @@ jobs:
         tar -cvf doc.tar.gz doc/book/*
 
     - name: Upload docs
-      uses: actions/upload-artifact@v3
+      uses: actions/upload-artifact@v4
       if: github.repository == 'GaloisInc/${{ env.NAME }}'
       with:
         name: "${{ env.NAME }}-docs"