fix: harden GitHub Actions workflows

Author: dagecko

.github/workflows/CI.yml

@@ -32,4 +32,4 @@ jobs:
         run: npm run coverage
 
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v4
+        uses: codecov/codecov-action@b9fd7d16f6d7d1b5d2bec1a2887e65ceed900238 # v4