Switch nugetsdkresolver back to the unstable version

Author: marcpopMSFT

eng/Version.Details.xml

@@ -143,7 +143,7 @@
       <Uri>https://dev.azure.com/dnceng/internal/_git/dotnet-aspnetcore</Uri>
       <Sha>215a587e52efa710de84138b0a3374b860b924d8</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.Build.NuGetSdkResolver" Version="6.12.4">
+    <Dependency Name="Microsoft.Build.NuGetSdkResolver" Version="6.12.4-rc.9">
       <Uri>https://github.com/nuget/nuget.client</Uri>
       <Sha>42bfb4554167e1d2fc2b950728d9bd8164f806c1</Sha>
     </Dependency>

eng/Versions.props

@@ -143,7 +143,7 @@
     <NuGetBuildTasksPackPackageVersion>6.12.4</NuGetBuildTasksPackPackageVersion>
     <NuGetCommandLineXPlatPackageVersion>6.12.4</NuGetCommandLineXPlatPackageVersion>
     <NuGetProjectModelPackageVersion>6.12.4</NuGetProjectModelPackageVersion>
-    <MicrosoftBuildNuGetSdkResolverPackageVersion>6.12.4</MicrosoftBuildNuGetSdkResolverPackageVersion>
+    <MicrosoftBuildNuGetSdkResolverPackageVersion>6.12.4-rc.9</MicrosoftBuildNuGetSdkResolverPackageVersion>
     <NuGetCommonPackageVersion>6.12.4</NuGetCommonPackageVersion>
     <NuGetConfigurationPackageVersion>6.12.4</NuGetConfigurationPackageVersion>
     <NuGetFrameworksPackageVersion>6.12.4</NuGetFrameworksPackageVersion>