v0.2.1: fix PRI/HTTP2-preface leak + shrink SNI-rewrite list #3

Job	Run time
build (x86_64-unknown-linux-gnu, ubuntu-latest, mhrv-rs-linux-amd64)	1m 42s
build (aarch64-unknown-linux-gnu, ubuntu-latest, mhrv-rs-linux-arm64)	2m 21s
build (aarch64-apple-darwin, macos-latest, mhrv-rs-macos-arm64)	2m 36s
build (x86_64-pc-windows-gnu, windows-latest, mhrv-rs-windows-amd64)	4m 39s
build (x86_64-apple-darwin, macos-latest, mhrv-rs-macos-amd64)	2m 18s
release	15s
	13m 51s

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