BUG: test for clean_warn breaks if not every inst_id / tag combo has a warning message for cleaning

[jklenzing]

Description

The current setup for test_clean_warn assumes that if the _clean_warn property is present, it is present for every tag.

pysat/pysat/tests/classes/cls_instrument_library.py

Lines 546 to 548 in 7bd8a23

	if hasattr(inst_dict['inst_module'], '_clean_warn'):
	clean_warn = inst_dict['inst_module']._clean_warn[
	inst_dict['inst_id']][inst_dict['tag']]

For some instruments (e.g., dmsp_sussi, timed_guvi) this is not true, and tests will fail when run.

To Reproduce this bug:

run pysatNASA tests with pysat 3.2.0

Options

• Use try / except notation in this test. If there is a KeyError present, tags do not exist for this combo and use pytest skip
• Use keys for all tag / inst_id combos, potentially with some other trigger to skip the test