Fallback to winbisonflex if flex is not found #16

Job	Run time
ubuntu-22.04, default debug	22s
windows-2022, default debug	1m 13s
macos-latest, default debug	35s
windows-2022, gcc debug	48s
ubuntu-22.04, clang debug	22s
ubuntu-22.04, sanitize debug	37s
windows-2022, sanitize+asanonly debug	1m 46s
ubuntu-22.04, clang+sanitize debug	54s
ubuntu-22.04, clang+msan debug	2m 0s
windows-2022, clang-cl+sanitize debug	2m 12s
windows-2022, clang-cl+msan debug	1m 28s
ubuntu-22.04, default release	21s
windows-2022, default release	45s
macos-latest, default release	29s
windows-2022, gcc release	56s
ubuntu-22.04, clang release	23s
ubuntu-22.04, sanitize release	34s
windows-2022, sanitize+asanonly release	1m 3s
ubuntu-22.04, clang+sanitize release	40s
ubuntu-22.04, clang+msan release	26s
windows-2022, clang-cl+sanitize release	59s
windows-2022, clang-cl+msan release	1m 2s
	19m 55s

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