O365 card is not properly serialized for Python and Expect replies

[denscollo]

Describe the bug

The content of the attachment for the O365 card is not getting properly serialized with the WaterfallSkillBot Python and expect replies delivery mode.

While in Normal mode the content of the attachment is a JSON object, when Expect Replies is set, the content is received as a string.

To Reproduce

Steps to reproduce the behavior:
O365 cards are not supported in Emulator, we can test it using WebChat.

1. Execute WaterfallHostBot and WaterfallSkillBot Python (link to branch) locally.

2. Use ngrok to tunnel the WaterfallHost bot port.

3. Create a Bot Channel Registration in Azure and use ngrok's URL as Messaging Endpoint.

4. Talk to the bot through WebChat and test the following:
   expectReplies - WaterfallSkill - WATERFALLSKILLBOTPYTHON - Cards - O365

5. See how the content of the attachment is shown.

Expected behavior

The content should be serialized as JSON.

Screenshots

These images show the attachment sent using Normal and ExpectReplies delivery modes