[Merged by Bors] - Update to go 1.21 #14708

Job	Run time
filter-changes	11s
lint	5m 37s
quicktests	1m 45s
unittests (ubuntu-latest)	14m 5s
unittests (macos-latest)	21m 49s
unittests (self-hosted, macos, arm64)	11m 3s
build (ubuntu-latest)	1m 18s
build (self-hosted, linux, arm64)	1m 15s
build (macos-latest)	1m 46s
build (self-hosted, macos, arm64)	58s
build (windows-latest)	5m 56s
unittests-slower (self-hosted, linux, arm64)	11m 48s
unittests-slower (windows-latest)	28m 54s
ci-status	3s
	1h 46m 28s

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