Use a nuget.config file

Author: JimBobSquarePants

nuget.config

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<configuration>
+  <packageSources>
+    <clear />
+      <!--Add Feedz.io restore sources while we wait for the ability to update shared infrastructure-->
+    <add key="nuget.org" value="https://api.nuget.org/v3/index.json" />
+    <add key="SixLabors" value="https://f.feedz.io/sixlabors/sixlabors/nuget/index.json"/>
+    <add key="dotnet" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-eng/nuget/v3/index.json"/>
+  </packageSources>
+</configuration>

src/ImageSharp.Drawing/ImageSharp.Drawing.csproj

@@ -13,16 +13,6 @@
     <Description>An extension to ImageSharp that allows the drawing of images, paths, and text.</Description>
     <TargetFrameworks>netcoreapp3.1;netcoreapp2.1;netstandard2.1;netstandard2.0;net472</TargetFrameworks>
   </PropertyGroup>
-
-  <!--Add Feedz.io restore sources while we wait for the ability to update shared infrastructure-->
-  <PropertyGroup>
-    <RestoreSources>
-      $(RestoreSources)
-      https://api.nuget.org/v3/index.json;
-      https://f.feedz.io/sixlabors/sixlabors/nuget/index.json;
-      https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-eng/nuget/v3/index.json;
-    </RestoreSources>
-  </PropertyGroup>
 
   <ItemGroup>
     <None Include="..\..\shared-infrastructure\branding\icons\imagesharp.drawing\sixlabors.imagesharp.drawing.128.png" Pack="true" PackagePath="" />