Fallback to winbisonflex if flex is not found #15

Job	Run time
ubuntu-22.04, default debug	21s
windows-2022, default debug	1m 16s
macos-latest, default debug	28s
windows-2022, gcc debug	47s
ubuntu-22.04, clang debug	22s
ubuntu-22.04, sanitize debug	38s
windows-2022, sanitize+asanonly debug	1m 44s
ubuntu-22.04, clang+sanitize debug	51s
ubuntu-22.04, clang+msan debug	1m 53s
windows-2022, clang-cl+sanitize debug	1m 25s
windows-2022, clang-cl+msan debug	1m 29s
ubuntu-22.04, default release	21s
windows-2022, default release	55s
macos-latest, default release	27s
windows-2022, gcc release	1m 10s
ubuntu-22.04, clang release	23s
ubuntu-22.04, sanitize release	35s
windows-2022, sanitize+asanonly release	1m 44s
ubuntu-22.04, clang+sanitize release	40s
ubuntu-22.04, clang+msan release	29s
windows-2022, clang-cl+sanitize release	1m 32s
windows-2022, clang-cl+msan release	1m 48s
	21m 18s

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