Bump codecov/codecov-action from 4 to 5

Bumps [codecov/codecov-action](https://github.com/codecov/codecov-action) from 4 to 5.
- [Release notes](https://github.com/codecov/codecov-action/releases)
- [Changelog](https://github.com/codecov/codecov-action/blob/main/CHANGELOG.md)
- [Commits](codecov/codecov-action@v4...v5)

---
updated-dependencies:
- dependency-name: codecov/codecov-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/buildtest.yaml

@@ -26,7 +26,7 @@ jobs:
       - name: Test
         run: dotnet test --configuration Release --collect:"Code Coverage;Format=Cobertura" --logger trx --results-directory TestResults --settings CodeCoverage.runsettings --no-build
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v4
+        uses: codecov/codecov-action@v5
         with:
           directory: ./TestResults
           files: '*.cobertura.xml'