Fix test failures under NumPy 1.24.

[copybara-service[bot]]

Fix test failures under NumPy 1.24.

NumPy 1.24 release notes: https://numpy.org/devdocs/release/1.24.0-notes.html

The fixes vary, but there are three particularly common changes:

• NumPy 1.24 removes a number of deprecated NumPy type aliases references (np.bool, np.int, np.float, np.complex, np.object, np.str, np.unicode, np.long). This change replaces them with their recommended replacements (bool, int, float, complex, object, str, str, int).
• Under NumPy 1.24 no longer automatically infers dtype=object when ragged sequences are passed to np.array(). See https://numpy.org/neps/nep-0034-infer-dtype-is-object.html . In most cases the fix is to pass dtype=object explicitly, but in some cases where the raggedness seems accidental other fixes were used.
• NumPy 1.24 is pickier about the dtype= option passed to comparison ufuncs.

[hhoppe]

Some notes:

• The github auto-workflow action failures are likely unrelated to this PR. sudo apt-get install ffmpeg is failing for unknown reason. An alternative might be https://github.com/marketplace/actions/setup-ffmpeg

• I installed numpy 1.24 on my machine. With it, I notice one warning when running pytest; it is on the test

  def test_to_type_extreme_value(self):
  types = ['uint8', 'uint16', 'uint32', 'uint64', 'float32', 'float64']

  There, omitting 'uint64' makes the warning go away --- I suggest doing that. It makes sense that 'uint64' would be a difficult format to support as it has more bits of precision than offered by computations using 'float64'.

• I suggest that we similarly remove 'uint64' from mediapy_examples.ipynb, instead of introducing the warning suppression suggested in this PR.