Pandas 3 compatibility

[soxofaan]

pandas 3 was released earlier this week and unit tests seem to be failing on that

=========================== short test summary info ============================
FAILED tests/extra/job_management/test_manager.py::TestMultiBackendJobManager::test_ensure_running_start_time_is_datetime[2024-09-01T09:00:00Z-2024-09-01T09:00:00Z-nan-2024-09-01T20:00:00Z-finished-21600] - TypeError: Invalid value '2024-09-01T10:00:00Z' for dtype 'float64'
FAILED tests/udf/test_run_code.py::test_get_annotation_str[Series-pandas.core.series.Series] - AssertionError: assert 'pandas.Series' == 'pandas.core.series.Series'
  
  - pandas.core.series.Series
  + pandas.Series
FAILED tests/udf/test_run_code.py::test_annotation_is_pandas_series - AssertionError: assert False is True
 +  where False = _annotation_is_pandas_series('pandas.core.series.Series')
=========== 3 failed, 2609 passed, 9 skipped, 165 warnings in 30.19s ===========