Add function 'tolowerUnicode' in sherpa-onnx-microphone (fix #791) #786

Job	Run time
ubuntu-latest Release shared	5m 57s
ubuntu-latest Release static	7m 7s
ubuntu-latest Debug shared	29m 28s
ubuntu-latest Debug static	27m 51s
macos-latest Release shared	7m 40s
macos-latest Release static	7m 3s
macos-latest Debug shared	22m 33s
macos-latest Debug static	22m 7s
	2h 9m 46s

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