pylint: Ignore different argument lengths for dnf callback.

It may or may not be used with a newer version of dnf. The callback
doesn't use the argument so just ignore it.

src/pylorax/dnfhelper.py

@@ -80,6 +80,8 @@ class LoraxDownloadCallback(dnf.callback.DownloadProgress):
         self.downloads[nevra] = done
         self._update()
 
+    # dnf 2.5.0 adds a new argument, accept it if it is passed
+    # pylint: disable=arguments-differ
     def start(self, total_files, total_size, total_drpms=0):
         self.total_files = total_files
         self.total_size = total_size