Fix tests to adapt to Qt 6.8's QNAM sending lowercase headers #112

Job	Run time
build (ubuntu-22.04, Debug, static, 5.15)	4m 36s
build (ubuntu-22.04, Debug, static, 6.5.*)	8m 10s
build (ubuntu-22.04, Debug, shared, 5.15)	6m 49s
build (ubuntu-22.04, Debug, shared, 6.5.*)	6m 10s
build (ubuntu-22.04, Release, static, 5.15)	1m 35s
build (ubuntu-22.04, Release, static, 6.5.*)	1m 40s
build (ubuntu-22.04, Release, shared, 5.15)	2m 25s
build (ubuntu-22.04, Release, shared, 6.5.*)	2m 12s
build (windows-2022, Debug, static, 5.15)	15m 50s
build (windows-2022, Debug, static, 6.5.*)	17m 33s
build (windows-2022, Debug, shared, 5.15)	17m 52s
build (windows-2022, Debug, shared, 6.5.*)	19m 41s
build (windows-2022, Release, static, 5.15)	2m 7s
build (windows-2022, Release, static, 6.5.*)	2m 17s
build (windows-2022, Release, shared, 5.15)	2m 44s
build (windows-2022, Release, shared, 6.5.*)	3m 16s
build (macos-12, Debug, static, 5.15)	9m 29s
build (macos-12, Debug, static, 6.5.*)	7m 31s
build (macos-12, Debug, shared, 5.15)	6m 32s
build (macos-12, Debug, shared, 6.5.*)	10m 40s
build (macos-12, Release, static, 5.15)	1m 47s
build (macos-12, Release, static, 6.5.*)	3m 5s
build (macos-12, Release, shared, 5.15)	2m 11s
build (macos-12, Release, shared, 6.5.*)	2m 23s
	2h 38m 35s

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