chore: add `CODEOWNERS` file #778

Job	Run time
Rust Clippy	1m 59s
Build & Test (stable, blocking-https)	1m 25s
Rust Docs	1m 49s
Build & Test (stable, async)	1m 28s
Build & Test (1.75.0, default)	2m 15s
Build & Test (stable, async-https-rustls-manual-roots)	1m 26s
Build & Test (stable, blocking-https-rustls)	1m 25s
Build & Test (stable, async-https-rustls)	2m 13s
Build & Test (stable, default)	2m 9s
Build & Test (1.75.0, async)	2m 5s
Build & Test (1.75.0, blocking-https-rustls)	1m 42s
Build & Test (1.75.0, blocking-https-native)	1m 36s
Build & Test (1.75.0, blocking-https)	1m 45s
Build & Test (stable, blocking-https-native)	1m 50s
Build & Test (1.75.0, async-https-rustls-manual-roots)	1m 45s
Build & Test (1.75.0, async-https-native)	1m 55s
Build & Test (1.75.0, blocking-https-bundled)	2m 43s
Rust Formatting	13s
Build & Test (stable, async-https)	1m 19s
Build & Test (1.75.0, async-https)	1m 42s
Build & Test (1.75.0, blocking)	1m 22s
Build & Test (stable, blocking-https-bundled)	2m 24s
Build & Test (1.75.0, async-https-rustls)	1m 55s
Build & Test (stable, blocking)	1m 4s
Build & Test (stable, async-https-native)	1m 34s
	43m 3s

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