build(deps): bump actions/upload-artifact from 5 to 6 (#75)

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 5 to 6.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v5...v6)

---
updated-dependencies:
- dependency-name: actions/upload-artifact
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Will Speak <lithiumflame@gmail.com>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -118,7 +118,7 @@ jobs:
         run: uv build
 
       - name: Upload build artifacts
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: dist
           path: dist/

.github/workflows/docs.yml

@@ -82,14 +82,14 @@ jobs:
           path: docs/_build/html
 
       - name: Upload documentation artifacts
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         if: github.event_name != 'release'
         with:
           name: documentation
           path: docs/_build/html
 
       - name: Upload build artifacts for debugging
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         if: failure()
         with:
           name: docs-build-artifacts