build(deps): bump actions/upload-artifact from 6 to 7

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 6 to 7.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v6...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/tests.yml

@@ -33,7 +33,7 @@ jobs:
         run: uv run coverage run --parallel -m pytest
       - name: Upload coverage data
         if: always() && matrix.python == '3.11'
-        uses: "actions/upload-artifact@v6"
+        uses: "actions/upload-artifact@v7"
         with:
           name: coverage-data
           path: ".coverage.*"
@@ -74,7 +74,7 @@ jobs:
       - name: Build docs
         run: uv run sphinx-build docs docs/_build
       - name: Upload documentation
-        uses: actions/upload-artifact@v6
+        uses: actions/upload-artifact@v7
         with:
           name: docs
           path: docs/_build