We have a number of unit tests that emit warnings, some of which are

errors in Python 3.11. These largely concern assertRaisesRegexp(),

inspect.getargspec(), and some bad escaping in test strings.
This updates all of our assertRaisesRegexp() calls to

assertRaisesRegex(), adds a decorator to skip tests if

inspect.getargspec() is not available, and fixes the string escaping.
This uncovered some bad comparisons that led to unittest2 not being

used on Python 2.7. Those have been updated to ensure we do properly

install and use that module.

Unit tests pass on Python 2.7 through 3.10.