pymsteams is not a supported library from Microsoft, its a 3p library. As a workaround can you please try and use without pymsteams and see if that works. Please try using curl/powershell - https://learn.microsoft.com/en-us/microsoftteams/platform/webhooks-and-connectors/how-to/connectors-using?tabs=cURL#send-messages-using-curl-and-powershell
Thanks,
Meghana
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