Fix new rubocop warnings

app/controllers/api/traces_controller.rb

@@ -101,7 +101,7 @@ module Api
       filename = "/tmp/#{rand}"
 
       # ...and save the uploaded file to that location
-      File.open(filename, "wb") { |f| f.write(file.read) }
+      File.binwrite(filename, file.read)
 
       # Create the trace object, falsely marked as already
       # inserted to stop the import daemon trying to load it