Bump Newtonsoft.Json to 12.0.3 (#136)

Author: Pliner

Source/EasyNetQ.Management.Client/EasyNetQ.Management.Client.csproj

@@ -46,7 +46,7 @@
     <PackageReference Include="System.Security.SecureString" Version="4.3.0" />
   </ItemGroup>
   <ItemGroup>
-    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" />
-    <PackageReference Include="Newtonsoft.Json" Version="10.0.3" />
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All" />
+    <PackageReference Include="Newtonsoft.Json" Version="12.0.3" />
   </ItemGroup>
 </Project>