feat: add codecov coverage reporting to CI workflow (#29)

Co-authored-by: MichaelEakins <michael.eakins@protonmail.com>

Author: CrashBytes

.github/workflows/react-compat.yml

@@ -36,8 +36,16 @@ jobs:
         run: |
           npm install --save-dev react@${{ matrix.react-version }} react-dom@${{ matrix.react-version }}
 
-      - name: Run tests
-        run: npm test
+      - name: Run tests with coverage
+        run: npm run test:coverage
+
+      - name: Upload coverage to Codecov
+        if: matrix.react-version == '18'
+        uses: codecov/codecov-action@v4
+        with:
+          files: ./coverage/lcov.info
+          flags: unittests
+          fail_ci_if_error: false
 
       - name: Type check
         run: npm run type-check