Fix printing version on Python 3

Don't crash when getting version from installed package.

Fixes: https://pagure.io/pungi/issue/1152
Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

pungi/__init__.py

@@ -26,7 +26,9 @@ def get_full_version():
         return re.sub(r'-1.fc\d\d?', '', output.strip().replace('pungi-', ''))
     else:
         import subprocess
-        proc = subprocess.Popen(["rpm", "-q", "pungi"], stdout=subprocess.PIPE)
+        proc = subprocess.Popen(
+            ["rpm", "-q", "pungi"], stdout=subprocess.PIPE, universal_newlines=True
+        )
         (output, err) = proc.communicate()
         if not err:
             return output.rstrip()