refactor(client)!: use `bitreq` for both `BlockingClient` and `AsyncClient` #783

Job	Run time
Rust Docs	42s
Rust Clippy	1m 13s
Rust Formatting	15s
Build & Test (stable, async-https)	29s
Build & Test (stable, async)	18s
Build & Test (stable, async-https-native)	29s
Build & Test (stable, blocking-https-native)	17s
Build & Test (stable, blocking-https)	29s
Build & Test (stable, async-https-rustls)	29s
Build & Test (stable, blocking)	27s
Build & Test (stable, blocking-https-rustls)	25s
Build & Test (stable, async-https-rustls-manual-roots)	30s
Build & Test (stable, default)	1s
Build & Test (stable, blocking-https-bundled)	14s
Build & Test (1.75.0, async)	23s
Build & Test (1.75.0, default)	1s
Build & Test (1.75.0, blocking-https-native)	25s
Build & Test (1.75.0, async-https-rustls-manual-roots)	24s
Build & Test (1.75.0, blocking-https-bundled)	1s
Build & Test (1.75.0, async-https-rustls)	23s
Build & Test (1.75.0, blocking)	22s
Build & Test (1.75.0, async-https-native)	24s
Build & Test (1.75.0, blocking-https)	17s
Build & Test (1.75.0, async-https)	1s
Build & Test (1.75.0, blocking-https-rustls)	1s
	9m 0s

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