Upgrade C# language version to 14.0 #419

Job	Run time
build-and-test-ubuntu-latest	42s
build-and-test-macos-latest	47s
build-and-test-windows-latest	50s
pack-and-publish	0s
build-and-test-ubuntu-latest	44s
build-and-test-windows-latest	50s
build-and-test-macos-latest	47s
pack-and-publish	0s
	4m 40s

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