support/scripts/pkg-stats: fix flake8 errors

support/scripts/pkg-stats: fix flake8 errors

support/scripts/pkg-stats:81:22: E211 whitespace before '('
support/scripts/pkg-stats:404:1: E305 expected 2 blank lines after class or function definition, found 1
support/scripts/pkg-stats:561:12: E713 test for membership should be 'not in'
support/scripts/pkg-stats:567:1: E302 expected 2 blank lines, found 1
support/scripts/pkg-stats:595:1: E302 expected 2 blank lines, found 1
support/scripts/pkg-stats:1051:1: E302 expected 2 blank lines, found 1
support/scripts/pkg-stats:1057:1: E302 expected 2 blank lines, found 1

Also fix:
support/scripts/pkg-stats:1054:5: E722 do not use bare 'except'
found by a more recent flake8 version. The exception may be either
IndexError or AttributeError, so use Exception to catch either.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>