Maintain compatibility with Python 3.13

[daskol]

Resolve #371.

[daskol]

Wheels dm-tree for Python 3.13 are missing. Building dm-tree from tarball with default gcc fails because of missing typedefs of uint8_t and uint64_t in absl/strings/internal/str_format/extension.h of vendored abseil library. Upstream issue is google-deepmind/tree#119.

[medaminezghal]

@daskol try to remove the "python_version < "3.13"" in the "https://github.com/google-deepmind/chex/blob/master/requirements/requirements-test.txt" file and rebuild the package.

[daskol]

@jakevdp Take a look at this PR, please. It became stale until I added support for Python 3.13 in google-deepmind/tree#123. Then Sergei Lebedev uploaded cp313 wheels in PyPI on the last days of January.

This branch is squashed and rebased on top of the latest changes in master.

[medaminezghal]

@stompchicken Could you approve this change and update the package to be compatible with python 3.13?

[daskol]

It seems that Google recently changed an indentation style (see here). I have adjusted test runner to preserve previous pylint configuration (indent width and E1120 error).

# String used as indentation unit.  The internal Google style guide mandates 2
# spaces.  Google's externaly-published style guide says 4, consistent with
# PEP 8.
indent-string='   '

[hbq1]

Thanks for adjusting the new pylint!