Replace deprecated PackageIcon

Author: andrewlock

assets/serilog-extension-nuget.png

@@ -13,7 +13,7 @@
     <PublicSign Condition=" '$(OS)' != 'Windows_NT' ">true</PublicSign>
     <PackageId>Serilog.Extensions.Logging</PackageId>
     <PackageTags>serilog;Microsoft.Extensions.Logging</PackageTags>
-    <PackageIconUrl>http://serilog.net/images/serilog-extension-nuget.png</PackageIconUrl>
+    <PackageIcon>serilog-extension-nuget.png</PackageIcon>
     <PackageProjectUrl>https://github.com/serilog/serilog-extensions-logging</PackageProjectUrl>
     <PackageLicenseExpression>Apache-2.0</PackageLicenseExpression>
     <RepositoryUrl>https://github.com/serilog/serilog-extensions-logging</RepositoryUrl>
@@ -23,6 +23,10 @@
     <LangVersion>7.3</LangVersion>
   </PropertyGroup>
 
+  <ItemGroup>
+    <None Include="..\..\assets\serilog-extension-nuget.png" Pack="true" PackagePath="" />
+  </ItemGroup>
+
   <ItemGroup>
     <PackageReference Include="Serilog" Version="2.8.0" />
     <PackageReference Include="Microsoft.Extensions.Logging" Version="2.0.0" />