Migrate to Google Analytics 4

[Benvii]

Migration to Google Analytics 4 need to be done as the configuration key google_analytics for theme ReadTheDoc is deprecated.

WARNING  -  Config value: 'google_analytics'. Warning: The configuration option google_analytics has been deprecated
            and will be removed in a future release of MkDocs. See the options available on your theme for an
            alternative.

It's also mentioned on the theme's page :

Is there anyone with access to the Google Analytics account to do it ?

If it's done we will be able to use mkdocs strict check en ensure there is no longer some broken links.