Project Management: Update Milestone It reference date

[aduth]

This pull request seeks to:

• Update the "Milestone It" reference date per July 22 delayed release
  • Since the next milestone date is calculated based on a two-week release cycle, this delay must be accounted for by manually updating the reference date
  • Ideally we can improve this further by referencing the due date of the previous milestone / current release. This will require more work to implement, since there is no easy way to search for a milestone from GitHub's milestone API without paginating results.
• Embed the merge action filtering into the custom Milestone It script
  • It is hoped this may improve reliability for inadvertent cancellations we have been seeing at this stage of the GitHub action workflow