Fix code verification in attach-binary-to-github lane (#26)

Author: sigabrtz

fastlane/Fastfile

@@ -111,7 +111,15 @@ lane :download_xcframework_from_nexus_and_attach_to_github_release do |options|
   UI.user_error!("Checksum in Package.swift does not match the checksum of the downloaded file.") unless package_swift_contains_checksum
 
   # Check if the downloaded xcframework file is signed and the signature is valid
-  sh "codesign --verify #{asset_file}" # Returns code 1 if the signature is invalid or the xcframework is not signed at all
+  # Extract the zip file to verify the signature
+  sh "unzip -q #{asset_file} -d ./Downloads/"
+  
+  # Find the .xcframework directory in the extracted content
+  xcframework_path = Dir.glob("./Downloads/*.xcframework").first
+  UI.user_error!("No .xcframework found in the extracted zip file.") unless xcframework_path
+  
+  # Verify the code signature
+  sh "codesign --verify #{xcframework_path}" # Returns code 1 if the signature is invalid or the xcframework is not signed at all
 
   # Upload the xcframework.zip to GitHub release
   asset_file = "./Downloads/#{File.basename(artefact_path)}"