migrate package icon to the new NuGet format

build/prepare-nuget-package.targets

@@ -13,6 +13,7 @@
     <Copy SourceFiles="$(ProjectDir)/package.nuspec" DestinationFolder="$(PackagePath)" />
     <Copy SourceFiles="$(SolutionDir)/../build/find-game-folder.targets" DestinationFolder="$(PackagePath)/build" />
     <Copy SourceFiles="$(ProjectDir)/build/smapi.targets" DestinationFiles="$(PackagePath)/build/Pathoschild.Stardew.ModBuildConfig.targets" />
+    <Copy SourceFiles="$(TargetDir)/assets/nuget-icon.png" DestinationFiles="$(PackagePath)/images/icon.png" />
     <Copy SourceFiles="$(TargetDir)/Newtonsoft.Json.dll" DestinationFolder="$(PackagePath)/build" />
     <Copy SourceFiles="$(TargetDir)/SMAPI.ModBuildConfig.dll" DestinationFolder="$(PackagePath)/build" />
     <Copy SourceFiles="$(TargetDir)/SMAPI.Toolkit.dll" DestinationFolder="$(PackagePath)/build" />

src/SMAPI.ModBuildConfig/SMAPI.ModBuildConfig.csproj

@@ -33,6 +33,12 @@
     </None>
   </ItemGroup>
 
+  <ItemGroup>
+    <None Update="assets\nuget-icon.png">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
+
   <Import Project="..\SMAPI.Internal\SMAPI.Internal.projitems" Label="Shared" />
   <Import Project="..\..\build\common.targets" />
   <Import Project="..\..\build\prepare-nuget-package.targets" />

src/SMAPI.ModBuildConfig/package.nuspec

@@ -10,6 +10,7 @@
     <license type="expression">MIT</license>
     <repository type="git" url="https://github.com/Pathoschild/SMAPI" />
     <projectUrl>https://smapi.io/package/readme</projectUrl>
+    <icon>images\icon.png</icon>
     <iconUrl>https://raw.githubusercontent.com/Pathoschild/SMAPI/develop/src/SMAPI.ModBuildConfig/assets/nuget-icon.png</iconUrl>
     <description>Automates the build configuration for crossplatform Stardew Valley SMAPI mods. For SMAPI 3.0 or later.</description>
     <releaseNotes>
@@ -24,6 +25,12 @@
       - Fixed Newtonsoft.Json.pdb included in release zips when Json.NET is referenced directly.
       - Fixed &lt;IgnoreModFilePatterns&gt; not working for i18n files.
       - Dropped support for older versions of SMAPI and Visual Studio.
+      - Migrated package icon to NuGet's new format.
     </releaseNotes>
   </metadata>
+  <files>
+    <file src="analyzers\**" target="analyzers" />
+    <file src="build\**" target="build" />
+    <file src="images\**" target="images" />
+  </files>
 </package>