fix(http1): use case-insensitive matching for trailer fields (#4011) #3174

Job	Run time
Verify hyper.h is up to date	1m 45s
Check Style	11s
semver	22s
udeps	26s
Check MSRV	8s
features	40s
Test C API (FFI)	37s
Test with Miri	2m 17s
Test cargo-c support (FFI)	23s
Test stable on windows-latest	2m 51s
Test nightly on macOS-latest	1m 39s
Test beta on macOS-latest	1m 20s
Test stable on macOS-latest	1m 35s
Test beta on ubuntu-latest	1m 8s
Test beta on windows-latest	2m 12s
Test nightly on ubuntu-latest	1m 7s
minimal-versions	31s
Test nightly on windows-latest	2m 27s
Test stable on ubuntu-latest	1m 1s
Build docs	22s
Check exposed types	20s
CI is green	0s
	23m 22s

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