Codecov integration

Author: lloc

.github/workflows/test.yml

@@ -10,3 +10,7 @@ jobs:
         run: composer install
       - name: Run Testsuite
         run: vendor/bin/phpunit
+      - name: Upload coverage reports to Codecov
+        uses: codecov/codecov-action@v4.0.1
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}