www/py-django32: Deprecate/Set to expire

• Set a deprecation note and let it expire to the end of June to give enough time to switch all affected ports over to Django 4.2 which is the next LTS release.
  
  The plan is to make every consumer ready for Django 4.2 during 2024Q1 and then switch everything to Django 4.2 after 2024Q2 has branched.

PR: 276319
Differential Revision: https://reviews.freebsd.org/D43344
With hat: python