Update to 3.1.3

Author: LarryKlugerDS

eg-03-csharp-auth-code-grant-core/eg-03-csharp-auth-code-grant-core.csproj

@@ -6,7 +6,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="DocuSign.eSign.dll" Version="3.1.3-rc" />
+    <PackageReference Include="DocuSign.eSign.dll" Version="3.1.3" />
     <PackageReference Include="Microsoft.AspNetCore.App" />
     <PackageReference Include="Microsoft.AspNetCore.Session" Version="2.1.1" />
     <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="2.1.1" />