osmo_interact_vty.py: fix py3 encoding bug

That code in common.py is hit when invoking via osmo_interact_vty.py. It has a
unicode string already, its attempt to decode hits a python exception (no
'decode' method).

Must be a long standing bug that no-one saw because we're only ever using
the osmo_verify_transcript_vty.py variant.

Change-Id: I1b4a629f12863c498a8681b555f57b4e255cebfb

osmopy/osmo_interact/common.py

@@ -429,7 +429,7 @@ def main_run_commands(run_app_str, output_path, cmd_str, cmd_files, interact):
 
         for f_path in (cmd_files or []):
             with open(f_path, 'r') as f:
-                interact.feed_commands(output, f.read().decode('utf-8').splitlines())
+                interact.feed_commands(output, f.read().splitlines())
 
         if not (cmd_str or cmd_files):
             while True: