Update Ruby deps for v3.3

[garaud]

• update the README file

• update the version of some dependencies

  Now you use a Ruby v3.3

• update the config about the sprockets tool for Javascript files

  As middleman v4 can handle .scss files, sprockets failed to compile some '.css'
  files which had been already compiled. Just told to sprockets to handle '.js' files.

• update the link to the main api page

  which is now to 'https://community.opendatasoft.com/p/developers'

How to Review

• mainly follow the README.md file which has been updated
• Ruby 3.2 or 3.3 should work
• check the build when you bundle exec middleman build and check one or more page when you bundle exec middleman serve
• the HTML pages should look like to the pages deployed in https://help.opendatasoft.com/apis/wfs-v2/#wfs-api for instance.