Bump actions/upload-artifact from 5 to 7 (#536)

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 5 to 7.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v5...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>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/build-pull-request.yml

@@ -14,7 +14,7 @@ jobs:
       - run: npm run build:ui
         working-directory: frontend
       - name: Export Mock Frontend
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v7
         if: github.event_name == 'pull_request'
         with:
           name: mock-frontend

.github/workflows/playwright-e2e.yml

@@ -111,7 +111,7 @@ jobs:
         run: npm run test:e2e
 
       - name: Upload test results
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v7
         if: always()
         with:
           name: playwright-results