activate.fish: support activating conda in fish shells

[d4l3k]

Description

This adds support for the fish shell #72

Test plan:

$ pytest conda_pack/tests/test_core.py

manual tests

$ conda-pack
$ tar xvf ~/conda-pack/conda-pack-3.10.tar.gz; . bin/activate.fish
$ which python3
$ deactivate

Checklist - did you ...

• Add a file to the news directory (using the template) for the next release's release notes?
• Add / update necessary tests?
• Add / update outdated documentation?

[conda-bot]

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In order for us to review and merge your code, please e-sign the Contributor License Agreement PDF. We then need to manually verify your signature, merge the PR (conda/infrastructure#956), and ping the bot to refresh the PR.

[d4l3k]

I signed the CLA

@conda-bot

[xhochy]

@d4l3k The tests are sadly failing in CI

[d4l3k]

@xhochy tests should be passing now -- I added fish as a conda-forge dep to the tests worklfow

[xhochy]

It still fails, we probably need to skip it on Windows.

[d4l3k]

@xhochy updated it to only install fish on mac/linux. test_activate is passing on mac/linux.

The failing mac test only failed on Py3.8 and seems to be flakiness unrelated to this PR.

[d4l3k]

@xhochy seems like all but 1 test is passing now. Looking at that failure I'm not sure how this PR could have caused it since I don't think I touched anything related to that file. Would appreciate your help in debugging this

I also don't have access to a mac environment where I could debug this locally

[xhochy]

Everything looks good now, needs someone to merge the CLA though (I cannot do that)

[travishathaway]

@conda-bot check

[travishathaway]

Should be good to go. Sorry for the delay!