Use correct property to disable upstream warnings.

Author: JimBobSquarePants

src/Directory.Build.props

@@ -18,7 +18,7 @@
 
   <!-- Compilation properties. -->
   <PropertyGroup Condition="'$(Configuration)' == 'Release'">
-    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    <!--<TreatWarningsAsErrors>true</TreatWarningsAsErrors>-->
   </PropertyGroup>
 
   <ItemGroup>

src/ImageSharp/ImageSharp.csproj

@@ -13,7 +13,6 @@
     <PackageTags>Image Resize Crop Gif Jpg Jpeg Bitmap Pbm Png Tga Tiff WebP NetCore</PackageTags>
     <Description>A new, fully featured, fully managed, cross-platform, 2D graphics API for .NET</Description>
     <Configurations>Debug;Release;Debug-InnerLoop;Release-InnerLoop</Configurations>
-    <WarningsAsErrors>false</WarningsAsErrors>
   </PropertyGroup>
 
   <PropertyGroup>