chore: Use ubuntu-latest in CI #1027

Job	Run time
Check with minimal Rust version	44s
Cargo test	40s
Cargo test (--all-features)	38s
Clippy (all code)	8s
Check	13s
Cargo test (--features alpha-async-tokio-rusqlite)	36s
Clippy (main package)	7s
Cargo test (--features from-directory)	38s
Code coverage	1m 34s
Documentation	11s
Rustfmt	3s
Mutation tests (0)	1m 16s
Mutation tests (1)	1m 2s
Mutation tests (2)	1m 9s
Mutation tests (3)	1m 7s
	10m 6s

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