flake8 E721

This error check has been added in a recent flake8 version and currently breaks the pipeline. The good news are that it's fairly trivial to fix and seems to just occur in 3 test files:

tests/analysis/test_analysis_run.py:98:24: E721 do not compare types, for exact checks use `is` / `is not`, for instance checks use `isinstance()`
tests/test_schwimmbad.py:64:20: E721 do not compare types, for exact checks use `is` / `is not`, for instance checks use `isinstance()`
tests/test_schwimmbad.py:66:20: E721 do not compare types, for exact checks use `is` / `is not`, for instance checks use `isinstance()`

see e.g. https://git.ligo.org/david-keitel/parallel_bilby/-/jobs/2900699