Bump dotnet/sdk from 9.0.302-bookworm-slim to 9.0.308-bookworm-slim in /docker #1231

Job	Run time
build-container / build-container (ubuntu-22.04-arm, alpine, linux-musl, arm64)	6m 14s
build-ubuntu1604-native / build-ubuntu1604-native-container	5m 8s
build-container / build-container (ubuntu-22.04, alpine, linux-musl, x64)	6m 44s
build / build (windows-2022, /c/ProgramData/OpenTelemetry .NET AutoInstrumentation/logs)	6m 12s
build / build (ubuntu-22.04-arm, /var/log/opentelemetry/dotnet)	5m 26s
build / build (ubuntu-22.04, /var/log/opentelemetry/dotnet)	5m 57s
build / build (macos-13, /var/log/opentelemetry/dotnet)	8m 7s
test-build-managed	-1s
build-nuget-packages	-1s
test-build-windows-container-tests	-1s
test-build-native	-1s
test-build-container	-1s
test-nuget-packages	0s
test-jobs	0s
	43m 43s

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