increase timeout of unittest in case fail on mac

Author: lucienwang1009

ci_build/azure_pipelines/templates/unit_test.yml

@@ -9,7 +9,7 @@ steps:
       export TF2ONNX_TEST_BACKEND=$CI_ONNX_BACKEND
       export TF2ONNX_TEST_OPSET=$CI_ONNX_OPSET
       python -m pytest --cov=tf2onnx --cov-report=term --disable-pytest-warnings -r s tests --cov-append
-    timeoutInMinutes: 5
+    timeoutInMinutes: 15
     displayName: ${{ format('Run UnitTest - Opset{0}', onnx_opset) }}
     condition: succeededOrFailed()
     env: