Google Calendar failed to get token (400 bad request)

### Widget link

https://github.com/glanceapp/community-widgets/tree/main/widgets/google-calendar-list-by-anant-j

### Description

Logs showing no error other than this on the page, showing request failure.

Start with the google-calendar-list-by-anant-j widget linked in the report and reproduce the token request while inspecting the reported 400 response. Done means identifying and fixing the token-request failure and confirming that the widget obtains a token without the reported error.

Written by the indexing model from the issue text.