Change to new PackageIcon property

As PackageIconUrl is deprecated

Author: matt-richardson

source/Halibut/Halibut.csproj

@@ -7,10 +7,10 @@
     <Authors>Octopus Deploy</Authors>
     <AssemblyName>Halibut</AssemblyName>
     <PackageId>Halibut</PackageId>
-    <PackageIconUrl>https://res.cloudinary.com/octopusdeploy/image/upload/v1422402724/halibut_f0zea8.png</PackageIconUrl>
     <PackageProjectUrl>https://github.com/OctopusDeploy/Halibut/</PackageProjectUrl>
     <PackageLicenseExpression>Apache-2.0</PackageLicenseExpression>
     <GenerateAssemblyTitleAttribute>false</GenerateAssemblyTitleAttribute>
+    <PackageIcon>icon.png</PackageIcon>
     <AllowedOutputExtensionsInPackageBuildOutputFolder>$(AllowedOutputExtensionsInPackageBuildOutputFolder);.pdb</AllowedOutputExtensionsInPackageBuildOutputFolder>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
@@ -54,4 +54,8 @@
     <DefineConstants>$(DefineConstants);NET40;HAS_REAL_PROXY;SUPPORTS_WEB_SOCKET_CLIENT</DefineConstants>
   </PropertyGroup>
 
+  <ItemGroup>
+    <None Include="icon.png" Pack="true" PackagePath="\" />
+  </ItemGroup>
+
 </Project>