bin: declare encoding in python scripts
It will solve this syntax error:
File "bin/pick-ui.py", line 2 SyntaxError: Non-ASCII character '\xc2' in file bin/pick-ui.py on line 2, but no encoding declared; see http://python.org/dev/peps/pep-0263/ for details
Signed-off-by: Andres Gomez agomez@igalia.com