Add ModelValidation to pipeline (#7152)

azure-pipelines.yml

@@ -16,6 +16,7 @@ jobs:
 - template: .azure-pipelines/Syntax.yml
 - template: .azure-pipelines/Semantic.yml
 - template: .azure-pipelines/Avocado.yml
+- template: .azure-pipelines/ModelValidation.yml
 - template: .azure-pipelines/BreakingChange.yml
 - template: .azure-pipelines/LintDiff.yml
 - template: .azure-pipelines/SwaggerToSDK.yml