www/py-graphite-web: Deprecate and set to expire

• The current version of py-graphite doesn't support Django 3.2, which is the next LTS (= long-term support) release since Django 2.2 reached its End-of-Life on April 11th [1].
  
  There may be a new release with support for newer versions of Django in the course of 2022Q2 to undeprecate the port.

PR: 261086, 261313 [1]
Approved by: bofh (maintainer, via D34859)