support: utils: use python3 explicitly

support: utils: use python3 explicitly

Python 2 is EOL sice 2020 [1], it's still available on distros, but may not
be installed by default (as being replaced by python3).

Thus remove compatibility imports:
from __future__ import print_function
from __future__ import absolute_import

Tested with python3 -m py_compile.

[1] https://www.python.org/doc/sunset-python-2/

Signed-off-by: Petr Vorel <petr.vorel@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>