[1.8.x] Update security.txt expiry to 2025-09-09 (#1494) #1326

Job	Run time
build-docker (internet.nl, docker/Dockerfile, app)	4m 46s
build-docker (unbound, docker/Dockerfile, unbound)	1m 44s
build-docker (linttest, docker/Dockerfile, linttest)	5m 30s
build-docker (test-runner, docker/test-runner.Dockerfile)	1m 51s
build-docker (webserver, docker/webserver.Dockerfile)	1m 11s
build-docker (grafana, docker/grafana.Dockerfile)	50s
build-docker (cron, docker/cron.Dockerfile)	1m 5s
integration-test	3m 6s
docs	1s
development-environment-test	2m 18s
batch-integration-test	2m 31s
lint/check	45s
test	2m 28s
	28m 6s

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