Adds a GitHub Action to test PyPI Releases on a Regular Schedule

[ilumsden]

This PR is created in response to hatchet/hatchet#443.

This PR adds a new GitHub Action that essentially performs automated regression testing on PyPI releases. It will install each considered version of Hatchet under each considered version of Python, checkout that Hatchet version's release branch, and perform the version's unit tests.

The following Hatchet versions are currently considered:

• v1.2.0 (omitted, missing writers module)
• v1.3.0 (omitted, missing writers module)
• v1.3.1a0 (omitted, missing writers module)
• 2022.1.0 (omitted, missing writers module)
• 2022.1.1 (omitted, missing writers module)
• 2022.2.0 (omitted, missing writers module)

Similarly, the following versions of Python are currently considered:

• 2.7 (omitted, missing version in docker)
• 3.5 (omitted, missing version in docker)
• 3.6
• 3.7
• 3.8
• 3.9

Before merging, the following tasks must be done:

• Replace the workflow_dispatch (i.e., manual) trigger with the commented out schedule trigger in pip_unit_tester.yaml Superseded by a task in a later comment
• Change the "Install Hatchet" step to install llnl-hatchet instead of hatchet. This will be changed once the llnl-hatchet package goes live on PyPI

[ilumsden]

Although the new GitHub Action is failing, the Action is actually working correctly. The following issues with pip-installed Hatchet are causing the Action to fail as expected:

1. For Python 2.7, the Cython extensions are not properly installed, leading to an ImportError whenever Hatchet tries to import them
2. For Python 3 (i.e., 3.5 - 3.8), the hatchet.writers module is not installed via pip. This is detailed in Adds the "hatchet.writers" module to pip installations #49

Since unit tests install Hatchet via python setup.py ..., these issues are unique to the pip-installed versions of Hatchet. Therefore, the fact that this Action is failing is actually a sign that the Action is working as intended

[ilumsden]

From my perspective, there are only 3 remaining tasks for this PR:

• If we want to do this before merging this PR, resolve the Cython import issue for Python 2.7
• If we want to do this before merging this PR, resolve and merge Adds the "hatchet.writers" module to pip installations #49
• Switch the trigger for this new Action from a workflow push to a schedule/cron event to prevent it from running too often

[ilumsden]

@slabasan now that we're only testing v2022.2.0 and we're not testing with Python 2.7, the runner is now passing. At this point, before merging, we should think about changing the trigger from a PR/branch push to a cron job. To that end, we need to choose how frequently we'd like this to run. Any ideas?

[ilumsden]

@slabasan I just set a schedule for the tester. According to GitHub, the cron syntax represents the following:

Runs at 00:00 UTC on the 1st in Jan, May, Aug and Nov.