File python3-support-bsc1070322.diff of Package btrfsmaintenance

As per explanation in https://bugzilla.suse.com/show_bug.cgi?id=1070322#c10
python3 must be called.
Index: btrfsmaintenance-0.4.1/btrfs-defrag-plugin.py
===================================================================
--- btrfsmaintenance-0.4.1.orig/btrfs-defrag-plugin.py
+++ btrfsmaintenance-0.4.1/btrfs-defrag-plugin.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 
 # This plugin defragments rpm files after update.
 #