support/testing/tests/package/sample_python_unittest_xml_reporting.py: fix flake8 warnings

Fixes:

support/testing/tests/package/sample_python_unittest_xml_reporting.py:4:1: E302 expected 2 blank lines, found 1
support/testing/tests/package/sample_python_unittest_xml_reporting.py:8:1: E305 expected 2 blank lines after class or function definition, found 1
1     E302 expected 2 blank lines, found 1
1     E305 expected 2 blank lines after class or function definition, found 1

Signed-off-by: Pierre-Jean Texier <texier.pj2@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>