ci: update codecov to use token

Author: saihaj

.github/workflows/validation.yml

@@ -28,6 +28,7 @@ jobs:
         run: yarn test:ci 
 
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v1
+        uses: codecov/codecov-action@v4
         with:
           fail_ci_if_error: true
+          token: ${{ secrets.CODECOV_TOKEN }}