Update Django to 4.2.16 #1582

Job	Run time
build-docker (internet.nl, docker/Dockerfile, app)	2m 52s
build-docker (unbound, docker/Dockerfile, unbound)	1m 19s
build-docker (linttest, docker/Dockerfile, linttest)	3m 20s
build-docker (test-runner, docker/test-runner.Dockerfile)	54s
build-docker (webserver, docker/webserver.Dockerfile)	1m 21s
build-docker (grafana, docker/grafana.Dockerfile)	50s
build-docker (util, docker/util.Dockerfile)	58s
lint/check	52s
batch-integration-test	2m 52s
docs	1s
development-environment-test	2m 14s
integration-test	3m 54s
test	2m 27s
	23m 54s

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