Replacing Cloud Functions for Github Actions

[pabluk]

In order to simplify and centralize the current notification workflow based on a webhook triggering Cloud Functions that parse a custom RSS feed, a new workflow will read the content generated on a branch and post it on the different channels (Telegram, Twitter, etc).

Basically it implies:

• Removing the current webhook setup
• Every post will generate an HTML and JSON file using https://gohugo.io/templates/output-formats/
• A Github workflow will be get these JSON files and pass them to a dedicated step for Telegram, Twitter, etc
• Scripts need to have tests
• Update this diagram https://github.com/sre-paris/reliability.re#publishing-workflow

[pabluk]

Now every published post has also an index.json file including all the fields. For example, see index.json.

[pabluk]

Done.

FYI @sterchelen I migrated the Cloud Functions for Telegram and Twitter here https://github.com/sre-paris/reliability.re/tree/main/scripts/ if you wanted to take a look at the format for Twitter and I will remove the other repo https://github.com/sre-paris/reliability.re-functions/,