tests/test_core.py does GlancesMain(args_begin_at=2) at module import
time, slicing the real process sys.argv. Passing --automake on the
pytest command line (rather than via PYTEST_ADDOPTS) shifted that
slice and broke it; set it via PYTEST_ADDOPTS instead.
Signed-off-by: Khem Raj <raj.khem@gmail.com>