feat: allow enabling http1/http2 individually #307

Job	Run time
Check Style	7s
Test with Miri	43s
features	43s
Check MSRV (1.63)	2m 49s
Test stable on ubuntu-latest	39s
Test stable on windows-latest	1m 14s
Test stable on macOS-latest	1m 20s
Test beta on ubuntu-latest	33s
Test beta on windows-latest	1m 17s
Test beta on macOS-latest	1m 3s
Test nightly on ubuntu-latest	34s
Test nightly on windows-latest	1m 20s
Test nightly on macOS-latest	1m 14s
Build docs	11s
CI is green	1s
	13m 48s

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