Add TabEntityContext to init.py (microsoft#1538)

Author: EricDahlvang

libraries/botbuilder-schema/botbuilder/schema/teams/__init__.py

@@ -63,6 +63,7 @@
 from ._models_py3 import MeetingParticipantInfo
 from ._models_py3 import CacheInfo
 from ._models_py3 import TabContext
+from ._models_py3 import TabEntityContext
 from ._models_py3 import TabRequest
 from ._models_py3 import TabResponseCard
 from ._models_py3 import TabResponseCards
@@ -136,6 +137,7 @@
  "MeetingParticipantInfo",
  "CacheInfo",
  "TabContext",
+ "TabEntityContext",
  "TabRequest",
  "TabResponseCard",
  "TabResponseCards",