[CI] sonic-config-engine now depends on SONiC YANG packages (sonic-net#198)

sonic-config-engine now depends on sonic-yang-mgmt and sonic-yang-models, so we now need to install them as part of continuous integration to get the CI working again

Author: jleveque

azure-pipelines.yml

@@ -45,6 +45,8 @@ steps:
     sudo pip2 install sonic_config_engine-1.0-py2-none-any.whl
     sudo pip3 install swsssdk-2.0.1-py3-none-any.whl
     sudo pip3 install sonic_py_common-1.0-py3-none-any.whl
+    sudo pip3 install sonic_yang_mgmt-1.0-py3-none-any.whl
+    sudo pip3 install sonic_yang_models-1.0-py3-none-any.whl
     sudo pip3 install sonic_config_engine-1.0-py3-none-any.whl
   workingDirectory: $(Pipeline.Workspace)/target/python-wheels/
   displayName: 'Install Python dependencies'