Prepare release 3.0.0 #14939

Job	Run time
Build and check documentation	3m 1s
Set up docker build 'dynamic' env variables	1s
End-to-end tests, chromium	13m 49s
End-to-end tests, firefox	16m 27s
Run the Django test suite	8m 12s
Run the Django test suite in reverse	5m 33s
End-to-end tests, webkit	12m 43s
docker_build (production) / Build image	2m 52s
docker_build (extensions, token_exchange,prefill_haalcentraalhr, all-extensions-) / Build image	2m 49s
Scan docker image	2m 5s
Simulate upgrading instances (2.7.4)	1m 31s
Simulate upgrading instances (2.7.8)	1m 20s
Check for unexepected OAS changes	4s
Generate SDKs from OAS	0s
Generate Postman collection from OAS	0s
Validate OAS	0s
Push Docker image	0s
update-docker-readme	0s
	1h 10m 27s

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