Use 5.0.0 previously-source-built tar.gz (#1955)

Author: dagood

eng/Versions.props

@@ -13,4 +13,7 @@
   <PropertyGroup>
     <PrivateSourceBuildReferencePackagesPackageVersion>1.0.0-beta.20607.1</PrivateSourceBuildReferencePackagesPackageVersion>
   </PropertyGroup>
+  <PropertyGroup>
+    <PrivateSourceBuiltArtifactsPackageVersion>0.1.0-5.0.100-920491-20201216</PrivateSourceBuiltArtifactsPackageVersion>
+  </PropertyGroup>
 </Project>