Centralise reference version management

Author: RussKie

Git.hub/Git.hub.csproj

@@ -6,7 +6,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="RestSharp" Version="106.6.10" />
+    <PackageReference Include="RestSharp" Version="$(RestSharpVersion)" />
   </ItemGroup>
 
 </Project>