Update python-absl-py to 0.8.0
- absltest.expectedFailureIf: a variant of unittest.expectedFailure that allows a condition to be given.
- Both Python 2 and Python 3 versions of tests are now created.
- assertTotallyOrdered no longer requires objects to implement __hash__.
- absltest now integrates better with --pdb_post_mortem.
- xml_reporter now includes timestamps to testcases, test_suite, test_suites elements.
- absl.logging no longer registers itself to logging.root at import time.