fix: add nuget_logo.png to Tool package to fix NU5046 pack error

The Tool project was missing the icon file include that all other packable
projects had, causing dotnet pack to fail with NU5046 in CI.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: elbruno

src/ElBruno.QRCodeGenerator.Tool/ElBruno.QRCodeGenerator.Tool.csproj

@@ -24,4 +24,8 @@
     <ProjectReference Include="..\ElBruno.QRCodeGenerator.Pdf\ElBruno.QRCodeGenerator.Pdf.csproj" />
   </ItemGroup>
 
+  <ItemGroup>
+    <None Include="$(MSBuildThisFileDirectory)..\..\images\nuget_logo.png" Pack="true" PackagePath="" />
+  </ItemGroup>
+
 </Project>