Update django minimum version to 2.2

Use Django from buster-backports as 1.11 is now deprecated.
16 jobs for fix-398 in 16 minutes and 56 seconds (queued for 4 seconds)
latest
Status Name Job ID Coverage
  Test
passed dispatcher-debian-10 #118236
amd64

00:02:17

passed dispatcher-debian-11 #118238
amd64

00:02:24

passed server-debian-10 #118237
amd64

00:03:00

passed server-debian-11 #118239
amd64

00:05:17

 
  Analyze
passed bandit-sast #118240
amd64-dind

00:00:58

passed black #118241
amd64

00:00:47

passed code_quality #118242
amd64

00:00:26

passed codespell #118247
amd64

00:00:23

passed coverage #118243
amd64

00:07:18

60.86%
passed dockerfiles #118244
amd64

00:00:20

passed pylint #118246
amd64

00:03:08

passed schemas #118245
amd64

00:00:32

 
  Build
passed debian/10 #118249
amd64

00:01:37

passed doc #118248
amd64

00:00:45

passed docker-amd64-dispatcher #118250
amd64-dind

00:03:55

passed docker-amd64-server #118251
amd64-dind

00:04:17