Update unit tests ci.

Signed-off-by: Jay Zhang <[email protected]>

Author: fatcat-z

.github/workflows/unit_tests_ci.yml

@@ -32,7 +32,6 @@ jobs:
             python_version: '3.10'
           - tf_version: '1.15.5'
             python_version: '3.7'
-            os: 'ubuntu-latest'
             opset_version: '15'
             ort_version: '1.14.1'
             onnx_version: '1.14.1'