Update test-backend-coreml.yml timeout

Author: metascroy

.github/workflows/test-backend-coreml.yml

@@ -43,5 +43,5 @@ jobs:
             && '["coreml"]'
             || '["coreml", "coreml_static_int8"]' }}
       ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
-      timeout: 120
+      timeout: 180
       run-macos: true