Update python-django-bootstrap4 to version 21.2 / rev 2 via SR 957223
    
    https://build.opensuse.org/request/show/957223
    by user mcepl + dimstar_suse
    - Update to 21.2:
      - Switch to a CalVer YY.MINOR versioning scheme. MINOR is
        the number of the release in the given year. This is the
        first release in 2021 using this scheme, so its version is
        21.1. The next version this year will be 21.2. The first
        version in 2022 will be 22.1.
      - Add support for Django 4.0 and Python 3.10 (#349).
      - Fix faulty example code
      - No line break in FileInput in horizontal layout.
      - Actually use the bundles JavaScript.
      - Drop support for Django 3.0, extended support stopped on
        2021-04-01.
      - Add support for Django 3.2.
      - Use bundled Bootstrap JavaScript, no need for separate popper.js.
      - Updated default Bootstrap to 4.6.0.
      - Add Dependabot for updates to dependencies.
      - Rename AUTHORS.md to AUTHORS, remove authors section fro