Bump Microsoft.NETFramework.ReferenceAssemblies package version

Author: drewnoakes

src/NetMQ/NetMQ.csproj

@@ -51,7 +51,7 @@
   </ItemGroup>
 
   <ItemGroup Condition=" '$(TargetFrameworkIdentifier)' == '.NETFramework' ">
-    <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.2" PrivateAssets="All" />
+    <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.3" PrivateAssets="All" />
     <PackageReference Include="System.Threading.Tasks.Extensions" Version="4.5.4" />
     <Reference Include="System.ServiceModel" />
     <Reference Include="System" />