Update to `hashbrown` 0.15 #448

Job	Run time
cargo check (msrv) (android) (armv7-linux-androideabi)	58s
cargo check (msrv) (windows-latest)	1m 40s
cargo check (msrv) (android) (aarch64-linux-android)	51s
cargo clippy (windows-latest)	2m 44s
cargo clippy (android) (armv7-linux-androideabi)	1m 5s
cargo check (msrv) (macos-latest)	49s
cargo clippy (android) (aarch64-linux-android)	1m 35s
cargo check (msrv) (android) (x86_64-linux-android)	31s
cargo clippy (macos-latest)	1m 4s
cargo check (msrv) (ubuntu-latest)	30s
cargo clippy (android) (x86_64-linux-android)	1m 44s
cargo clippy (ubuntu-latest)	1m 8s
cargo fmt	22s
cargo doc (windows-latest)	2m 16s
cargo test (windows-latest)	2m 53s
cargo doc (macos-latest)	1m 6s
typos	5s
cargo test (macos-latest)	1m 3s
cargo doc (ubuntu-latest)	35s
cargo test (ubuntu-latest)	55s
	23m 54s

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