The cake-contrib icon will be automatically included in the project, unless
CakeContribGuidelinesIconOmitImport is set to True.
To to use a "custom" import the following could be used:
<PropertyGroup>
<CakeContribGuidelinesIconOmitImport>True</CakeContribGuidelinesIconOmitImport>
<PackageIcon>logo.png</PackageIcon>
</PropertyGroup>
<ItemGroup>
<None Include="icons/logo.png" Pack="True" PackagePath="" />
</ItemGroup>