Increase available calls to GithHub API

[dodu94]

Unauthorized GitHub API calls (i.e., one at beginning of execution of the app to get the tree of available files) is limited to 60 calls/h. It can be increased to thousands if the requests are authenticated.

solution 1) authenticate the request using a personal token as specified here in combination with streamlit secrets to store the token

solution 2) add a git action calling the API every hour (or more) to adjourn the tree in a file somewhere?