Update to use tf 2.3.0

Signed-off-by: Tom Wildenhain <[email protected]>

Author: TomWildenhain-Microsoft

ci_build/azure_pipelines/pretrained_model_test.yml

@@ -4,7 +4,7 @@ jobs:
 - template: 'templates/job_generator.yml'
   parameters:
     python_versions: ['3.7']
-    tf_versions: ['1.15.2','2.1.0']
+    tf_versions: ['1.15.2','2.3.0']
     job:
       steps:
       - template: 'pretrained_model_test.yml'