Rust

Merge pull request #281 from sourcefrog/transport-ref #1223

Job	Run time
clippy	29s
quick-test	55s
rustfmt	9s
build-all-features	49s
tests (ubuntu-latest, stable)	1m 22s
tests (ubuntu-latest, nightly)	1m 17s
tests (ubuntu-latest, 1.79)	1m 43s
cargo-mutants (0)	14m 29s
pr-mutants	0s
tests (windows-latest, stable)	3m 52s
cargo-mutants (1)	13m 26s
tests (windows-latest, nightly)	3m 23s
cargo-mutants (2)	14m 35s
tests (windows-latest, 1.79)	3m 17s
cargo-mutants (3)	14m 6s
tests (macOS-latest, stable)	3m 27s
tests (macOS-latest, nightly)	3m 34s
cargo-mutants (4)	10m 43s
tests (macOS-latest, 1.79)	3m 30s
cargo-mutants (5)	11m 39s
cargo-mutants (6)	12m 50s
cargo-mutants (7)	15m 45s
cargo-mutants (8)	9m 44s
cargo-mutants (9)	8m 49s
	2h 33m 53s

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