Bump Verify.Xunit from 20.8.2 to 26.1.5 #268

Job	Run time
build-centos-native / build-centos-native-container	4m 38s
build-container / build-container (ubuntu-20.04, alpine, linux-musl, x64)	21s
build-container / build-container (actuated-arm64-4cpu-8gb, alpine, linux-musl, arm64)	1s
build / build (windows-2022, /c/ProgramData/OpenTelemetry .NET AutoInstrumentation/logs)	3m 22s
build / build (ubuntu-20.04, /var/log/opentelemetry/dotnet)	1m 35s
build / build (macos-11, /var/log/opentelemetry/dotnet)	1s
build / build (actuated-arm64-4cpu-8gb, /var/log/opentelemetry/dotnet)	1s
build-nuget-packages	0s
test-build-native	0s
test-build-container	0s
test-build-managed	0s
test-build-windows-container-tests	0s
test-nuget-packages	0s
test-jobs	0s
	9m 59s

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