[MRG] Update GitHub actions

[gtdang]

Runners were no longer finding the conda base version preventing gh runners to build.

• Updating the setup-miniconda line to version 3 seemed to fix the problem.
• Updated the checkout action to v4.
• Changed fetch-depth to 2 because it was stalling on codecov step on linux runners. source
• Updated to use codecov upload action v4 instead of shell command

setup-miniconda checkout

[gtdang]

@ntolley @jasmainak @rythorpe I will need to work with someone who has access to the codecov token to set-up the secret for the repository. Can someone meet with me tomorrow for this?

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 92.69%. Comparing base (d28ddb7) to head (c167263). Report is 32 commits behind head on master.

:exclamation: Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #758 +/- ## ========================================== + Coverage 92.67% 92.69% +0.02% ========================================== Files 27 27 Lines 4928 4969 +41 ========================================== + Hits 4567 4606 +39 - Misses 361 363 +2 ``` | [Flag](https://app.codecov.io/gh/jonescompneurolab/hnn-core/pull/758/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jonescompneurolab) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/jonescompneurolab/hnn-core/pull/758/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jonescompneurolab) | `92.69% <ø> (?)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jonescompneurolab#carryforward-flags-in-the-pull-request-comment) to find out more.

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[gtdang]

@ntolley @jasmainak @rythorpe I will need to work with someone who has access to the codecov token to set-up the secret for the repository. Can someone meet with me tomorrow for this?

Actually we don't need to meet for this if one of you can do it following these directions. Note the token is needed for PRs that come from within the org. It switches to token-less uploading if the PR is coming from a forked repository. See more information here.

[jasmainak]

I'll try to help if I can find a moment tomorrow ...