Extend ModelCatalog default action distribution to support torch dirichlet distribution

[MattiasDC]

The default ModelCatalog.get_action_dist now supports Dirichlet distributions when using the torch framework. This is useful when the Simplex action space is used when using torch.

Why are these changes needed?

Extend the default functionality to support Dirichlet distributions, needed for Simplex action spaces, when using torch.

Related issue number

Closes #32657

Checks

• [X] I've signed off every commit(by using the -s flag, i.e., git commit -s) in this PR.
• [X] I've run scripts/format.sh to lint the changes in this PR.
• [] I've included any doc changes needed for https://docs.ray.io/en/master/.
• [X] I've made sure the tests are passing. Note that there might be a few flaky tests, see the recent failures at https://flakey-tests.ray.io/
• Testing Strategy
  • [X] Unit tests
  • [ ] Release tests
  • [ ] This PR is not tested :(

[MattiasDC]

I'm suspecting some flakyness in the tests here, is there any way I can rerun the tests?

[stale[bot]]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 14 days if no further activity occurs. Thank you for your contributions.

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[MattiasDC]

@sven1977 this has been marked as stale, could someone do a review?

[stale[bot]]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 14 days if no further activity occurs. Thank you for your contributions.

• If you'd like to keep this open, just leave any comment, and the stale label will be removed.

[MattiasDC]

@sven1977 this has been marked as stale, could someone do a review?

[stale[bot]]

Hi again! The issue will be closed because there has been no more activity in the 14 days since the last message.

Please feel free to reopen or open a new issue if you'd still like it to be addressed.

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Thanks again for opening the issue!

[MattiasDC]

@avnishn, why was this closed? Am I missing a procedure to let this be reviewed?

[avnishn]

I am terribly sorry we just missed this contribution, but it looks good with me.

[MattiasDC]

Hi @avnishn , I think the failed tests are flaky, can you confirm and merge if everything is ok?

[stale[bot]]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 14 days if no further activity occurs. Thank you for your contributions.

• If you'd like to keep this open, just leave any comment, and the stale label will be removed.

[MattiasDC]

@avnishn ?