Disable test for updated generated code on upgradeable contracts

.github/workflows/checks.yml

@@ -34,6 +34,7 @@ jobs:
           ENABLE_GAS_REPORT: true
       - run: npm run test:inheritance
       - run: npm run test:generation
+        if: github.repository != 'OpenZeppelin/openzeppelin-contracts-upgradeable'
 
   coverage:
     if: github.repository != 'OpenZeppelin/openzeppelin-contracts-upgradeable'