add __init__.py for capabilities (microsoft#1177)

* Create __init__.py

* Update __init__.py

* Update __init__.py

Fix formatting to satisfy black.

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Co-authored-by: Ricky Loynd <[email protected]>

Author: btcioner

autogen/agentchat/contrib/capabilities/__init__.py

@@ -0,0 +1,5 @@
+from .teachability import Teachability
+from .agent_capability import AgentCapability
+
+
+__all__ = ["Teachability", "AgentCapability"]