ci: Remove llvm 5, introduce llvm 16 #1850

Job	Run time
rustfmt-clippy	31s
minimal	17s
docs	18s
check-cfg	21s
msrv	2m 52s
quickchecking	18s
test-book	6s
test (ubuntu-latest, 9.0, 1, 0, 0, 0, 0)	1m 50s
test-expectations (ubuntu-latest)	56s
test (ubuntu-latest, 9.0, 1, 0, 0, 1, 0)	1m 52s
test-expectations (macos-latest)	2m 7s
test (ubuntu-latest, 9.0, 1, 0, 1, 0, 0)	2m 14s
test (ubuntu-latest, 9.0, 1, 0, 1, 1, 0)	2m 7s
test (ubuntu-latest, 9.0, 1, 1, 0, 0, 0)	2m 37s
test (ubuntu-latest, 9.0, 1, 1, 0, 1, 0)	2m 46s
test (ubuntu-latest, 9.0, 1, 1, 1, 0, 0)	2m 29s
test (ubuntu-latest, 9.0, 1, 1, 1, 1, 0)	2m 16s
test (ubuntu-latest, 16.0, 1, 0, 0, 0, 0)	2m 31s
test (ubuntu-latest, 16.0, 1, 0, 0, 1, 0)	2m 35s
test (ubuntu-latest, 16.0, 1, 0, 1, 0, 0)	3m 0s
test (ubuntu-latest, 16.0, 1, 0, 1, 1, 0)	4m 15s
test (ubuntu-latest, 16.0, 1, 1, 0, 0, 0)	3m 10s
test (ubuntu-latest, 16.0, 1, 1, 0, 1, 0)	3m 6s
test (ubuntu-latest, 16.0, 1, 1, 1, 0, 0)	3m 16s
test (ubuntu-latest, 16.0, 1, 1, 1, 1, 0)	3m 5s
test (ubuntu-latest, 16.0, 0, 0, 1)	2m 13s
	53m 8s

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