chore(ci): bump actions/upload-artifact from 4 to 7

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 4 to 7.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v4...v7)

---
updated-dependencies:
- dependency-name: actions/upload-artifact
  dependency-version: '7'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -44,7 +44,7 @@ jobs:
         run: uv run pytest -m "not slow and not integration and not perf" --cov=volscope --cov-report=xml --cov-fail-under=65
 
       - name: Upload coverage
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         if: matrix.python-version == '3.12'
         with:
           name: coverage-xml