Add action to sync open pull requests to Asana

[sammacbeth]

Reviewer:

Description:

Adds a new workflow that adds and updates PR tasks in Asana.

Steps to test this PR:

Unfortunately, pull_request_target actions only start working after they get merged into the main branch, so we can't test this ahead of time.

Automated tests:

• Unit tests
• Integration tests

Reviewer Checklist:

• Ensure the PR solves the problem
• Review every line of code
• Ensure the PR does no harm by testing the changes thoroughly
• Get help if you're uncomfortable with any of the above!
• Determine if there are any quick wins that improve the implementation

PR Author Checklist:

• Get advice or leverage existing code
• Agree on technical approach with reviewer (if the changes are nuanced)
• Ensure that there is a testing strategy (and documented non-automated tests)
• Ensure there is a documented monitoring strategy (if necessary)
• Consider systems implications

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• To see the specific tasks where the Asana app for GitHub is being used, see below:
  • https://app.asana.com/0/0/1203910934070539