Backporting fixes:
- Fix rotbaum random seed and num_samples argument. (#2408 by @sighellan)
- Hierarchical: Make sure the input S matrix is of right dtype (#2415 by @rshyamsundar)
- Mypy fixes (#2427 by @jaheba)
- Speed up PandasDataset for long dataframes (#2435 by @lostella)
- Fix frequency inference in PandasDataset (#2442 by @lostella)
- Tests: Change Python versions. (#2448 by @jaheba)