CI: build with `--locked`, and add one job for stable build without `… #854

Job	Run time
Check (not locked)	18s
Check (stable)	15s
Check (1.67.1)	1m 54s
Check All Features (1.67.1)	2m 4s
Rustfmt	7s
Check All Features (nightly)	24s
Check semver compatibility	42s
Check All Features (stable)	16s
Check (nightly)	22s
Test Suite	30s
Clippy	23s
Build documentation	35s
Test suite (with features) (--features=default)	30s
Test suite (with features) (--no-default-features)	27s
Test suite (with features) (--features=verify)	41s
Test suite (with features) (--all-features)	21s
Test suite (with features) (--features=validate)	30s
	10m 19s

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