Change dependencies for Python 3.10 support

[norabelrose]

Currently, imitation does not work properly on Python 3.10 due to its reliance on the PyPI version of Sacred (0.8.2). In particular, if you try to run python -m imitation.scripts.train_rl, you'll get errors like this:

Exception originated from within Sacred.
Traceback (most recent calls):
  File "/opt/homebrew/Caskroom/miniforge/base/lib/python3.10/site-packages/sacred/utils.py", line 345, in recursive_update
    if isinstance(v, collections.Mapping):
AttributeError: module 'collections' has no attribute 'Mapping'

The Mapping type was removed from the collections library in Python 3.10. The GitHub version of Sacred was actually updated for Python 3.10 back in March (it's now on 0.8.3), but unfortunately the maintainer in charge of pushing new releases to PyPI seems to be MIA (see IDSIA/sacred#857), so it's not clear when the PyPI package will be updated. This PR fixes the issue by simply changing the Sacred dependency in setup.py to the GitHub version.

I also noticed that the tests currently require an out-of-date version of Ray Tune (~=0.8.5), but Ray just added support for Python 3.10 in its most recent release a few days ago (1.13.0). So I changed that dependency from ~=0.8.5 to >=0.8.5 to allow for downloading the most recent version for testing.

[AdamGleave]

Thanks for the PR! Couple of minor points about what versions we should specify but generally happy with the upgrade.

Note CI will still be running on 3.8 as Dockerfile not changed. But we probably want that so long as we want to maintain compatibility with 3.8, as Python is backwards compatible more likely to break on 3.8 and not 3.10 than vice-versa.

[codecov]

Codecov Report

Merging #446 (2933864) into master (f332680) will decrease coverage by 0.39%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master     #446      +/-   ##
==========================================
- Coverage   96.96%   96.56%   -0.40%     
==========================================
  Files          79       79              
  Lines        6264     6263       -1     
==========================================
- Hits         6074     6048      -26     
- Misses        190      215      +25     

Impacted Files	Coverage Δ
src/imitation/scripts/parallel.py	64.06% <0.00%> (-32.87%)	⬇️
src/imitation/scripts/config/train_adversarial.py	63.63% <0.00%> (-3.90%)	⬇️
src/imitation/scripts/train_adversarial.py	94.28% <0.00%> (-1.43%)	⬇️

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[AdamGleave]

Fixes #399

[AdamGleave]

LGTM