Upgrade `bitflags` to from 1.2 to 2.4 #108

Job	Run time
build (ubuntu-latest, 1.58.0)	5m 39s
build (ubuntu-latest, stable)	34s
build (ubuntu-latest, beta)	42s
build (ubuntu-latest, nightly)	37s
build (macos-latest, 1.58.0)	7m 13s
build (macos-latest, stable)	51s
build (macos-latest, beta)	1m 7s
build (macos-latest, nightly)	50s
build (windows-latest, -x86_64-pc-windows-msvc, 1.58.0)	5m 42s
build (windows-latest, -x86_64-pc-windows-msvc, stable)	1m 40s
build (windows-latest, -x86_64-pc-windows-msvc, beta)	1m 53s
build (windows-latest, -x86_64-pc-windows-msvc, nightly)	1m 41s
build (windows-latest, -i686-pc-windows-msvc, 1.58.0)	7m 21s
build (windows-latest, -i686-pc-windows-msvc, stable)	1m 39s
build (windows-latest, -i686-pc-windows-msvc, beta)	2m 6s
build (windows-latest, -i686-pc-windows-msvc, nightly)	1m 12s
	40m 47s

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