Add .NET 9 to the version support matrix #953

Job	Run time
cleanup-code (ubuntu-latest)	21m 20s
build-and-test (ubuntu-latest)	7m 39s
cleanup-code (windows-latest)	24m 0s
inspect-code (ubuntu-latest)	6m 24s
build-and-test (windows-latest)	11m 36s
cleanup-code (macos-latest)	13m 20s
inspect-code (windows-latest)	9m 21s
build-and-test (macos-latest)	6m 12s
inspect-code (macos-latest)	5m 28s
publish	17s
	1h 45m 37s

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