[bug] use decodebytes

decodestring is an alias that was deprecated in 3.1

- Resolves: #412

branding/templates/snap/hooks/install

@@ -6,7 +6,7 @@
 # by the script at "snap/pre/pack_installers"
 import subprocess
 import os
-from base64 import decodestring as decode
+from base64 import decodebytes as decode
 
 POLKIT = b'PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0iVVRGLTgiPz4KPCFET0NUWVBFIHBvbGljeWNv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\nb25maWc+Cg==\n'