Add a code of conduct #106

Job	Run time
Audit dependencies	40s
Clippy (x86_64-unknown-linux-gnu, false, true)	1m 9s
Format	7s
Build and test (stable, ubuntu-latest, x86_64-unknown-linux-gnu)	1m 39s
Clippy (armv7-unknown-linux-gnueabihf, true, false, -target arm-linux-gnueabihf -mcpu=generic+v7a...	44s
Smoke-test fuzzing targets	3m 50s
Clippy (x86_64-unknown-linux-musl, true, false, -target x86_64-linux-musl)	31s
Build and test (beta, ubuntu-latest, x86_64-unknown-linux-gnu)	1m 2s
Validate man pages	11s
Smoke-test fuzzing targets (--all-features)	1m 45s
Clippy (x86_64-apple-darwin, true, false, -target x86_64-macos-gnu -g)	51s
Build and test (1.66.0, ubuntu-latest, x86_64-unknown-linux-gnu)	1m 16s
Build and test (stable, ubuntu-latest, x86_64-unknown-linux-musl)	1m 42s
Build and test (stable, macos-latest, x86_64-apple-darwin)	1m 40s
Check unused dependencies	1m 51s
Validate configs	31s
Build and test (stable, ubuntu-latest, --all-features, x86_64-unknown-linux-gnu)	1m 56s
Build and test (1.66.0, ubuntu-latest, --all-features, x86_64-unknown-linux-gnu)	1m 9s
Build and test (stable, ubuntu-latest, --all-features, x86_64-unknown-linux-musl)	1m 4s
Build and test (stable, macos-latest, --all-features, x86_64-apple-darwin)	1m 20s
	24m 58s

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