Merge branch '7.3' into 7.4

* 7.3:
  Postal mailer transport message ID retrieval
  Bump Symfony version to 7.3.7
  Update VERSION for 7.3.6
  Update CHANGELOG for 7.3.6
  Bump Symfony version to 6.4.29
  Update VERSION for 6.4.28
  Update CONTRIBUTORS for 6.4.28
  Update CHANGELOG for 6.4.28
  [Validator] Reviewed and corrected Belarussian translations for the Validator component in the validators.be.xlf file

Author: nicolas-grekas