Fix invalid adaptive card body for Webex sink

[ppmathis]

This PR fixes an issue with the currently used adaptive card body for the Webex sink. I installed the latest Robusta version 0.10.30 in a test environment of mine and noticed an issue once I configured a Webex sink, specifically that the notification messages only show up properly in the web client for Cisco Webex. When attempting to view the messages in the desktop clients (Windows / macOS), the app only showed the placeholder text message (.) without any other data.

Screenshot from Webex Web:

Screenshot from Webex Desktop (macOS):

So I started analysing this issue by dumping the adaptive card data into a file and messing around with it, until I discovered that the sent payload is violating the official Adaptive Cards v1.2 spec as the property wrap is set as a string with a boolean inside, instead of an actual boolean. So the JSON body should contain "wrap": true, not "wrap": "true" like it does today.

While the Webex web client still properly displays such semi-broken cards, the desktop client straight up refuses without any useful information. Simply switching out the couple lines of code to pass True instead of "true" fully fixes the issue on both platforms.

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[arikalon1]

Nice find!
Thank you for the PR @ppmathis