Update .NET to version 8 #12264

Job	Run time
setup-environment	46s
tidy	1m 1s
gofmt	4m 42s
generate-metrics	4m 33s
lint	7m 24s
coverage	8m 41s
test	3m 12s
cross-compile (binaries-darwin_amd64)	4m 57s
cross-compile (binaries-darwin_arm64)	5m 0s
cross-compile (binaries-linux_amd64)	5m 4s
cross-compile (binaries-linux_arm64)	4m 47s
cross-compile (binaries-windows_amd64)	4m 49s
cross-compile (binaries-linux_ppc64le)	4m 44s
	59m 40s

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