Upgrade to .NET 9.0 #298

Job	Run time
Test Cloud Framework	1m 55s
Test StringEnum Trimmed	49s
Timestamp	5s
Build Windows UEFS	1m 17s
Build Windows Shim	1m 39s
Build Linux Pass 1	5m 33s
Build and Test Libraries on Windows	8m 34s
Build macOS Pass 1	4m 26s
Build Windows Pass 1	6m 13s
Build Linux Shim	45s
Build macOS Shim	53s
Build macOS UEFS	55s
Build and Test Libraries on Linux	6m 23s
Build Libraries on macOS	5m 5s
Build Windows Pass 2	0s
Build Linux Pass 2	0s
Build macOS Pass 2	0s
Test Schema Generation	0s
Publish UET Container (with Wine)	0s
Publish UET Container	0s
Publish UEFS Container	0s
Publish to GitHub	0s
Publish to NuGet	0s
	44m 32s

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