Add GHA deleting closed and unmerged PRs from Project Board

[christinaor]

Fixes #4357

What changes did you make and why did you make them ?

• Added a GitHub Action (GHA) to delete closed but unmerged PRs from the Project Board. This addition was made because we want to optimize the Project Board, but the sheer number of cards are slowing it down.
• The GHA was tested locally and PRs were successfully removed from the Project Board after being closed. This did not affect other open PRs that were also unmerged.
• PRs that would be closed were also tested in different columns of the Project Board. The results were the same.

No screenshots are available since there are no visible changes to the website, but reviewers should be able to find the comments I made in the PRs for my "website" repo when I was testing the GHA and should be able to replicate the results using the resources. Let me know if there are any questions though!

[github-actions]

Want to review this pull request? Take a look at this documentation for a step by step guide!

From your project repository, check out a new branch and test the changes.

git checkout -b christinaor-add-gha-to-delete-closed-unmerged-prs-4357 gh-pages
git pull https://github.com/christinaor/website.git add-gha-to-delete-closed-unmerged-prs-4357

[se7en-illa]

Availability: M-F 12:00PM - 8:00PM EST
ETA: EOD 04/26/2023

[angieyan]

Availability: M-Thurs 1:00PM - 2:30PM PST, Sunday 9am - 12pm PST
ETA: EOD 4/30/2023

[t-will-gillis]

Hey @christinaor - fantastic job! I was able to test this GHA on a mock Project Board. PRs in the default column "PR Needs review..." which were then closed -without being reviewed- were subsequently removed from the board. I also tested PRs with approvals and PRs with changes requested. When closed without merging these PRs were also removed from the board.

From that standpoint, this GHA is successful. In the future this will help reduce clutter by automatically removing PRs when they are closed without merging. Great job again!

One important note for the HfLA team: the GHAs appear to be triggered by changes in a n issue's status. On my mock Project Board, pre-existing, closed PRs were not affected by this GHA and it is likely this will be true on the current Project Board also. >>> Along with other pre-existing merged PRs these closed PRs will likely need to be deleted manually.

[roslynwythe]

@angieyan Please let us know if you are still able to review the PR, and if so please post your availability and ETA.

[angieyan]

@roslynwythe Hi Roslyn. Yes I will review this PR today and tomorrow morning.
Blocks: Testing some GHA
Availability: Wed 8:00-9:00 PM PST, Thur 9am - 12pm PST
ETA: EOD 5/4/2023

[angieyan]

Good job @christinaor . I tested the changes, and they removed the closed issue from the board. Thank you for your work, and have a nice day!