feat: action to modify issue/PR TargetDate when a special comment is posted

[kelly-sovacool]

Description of feature

This would allow Trello x Unito to adjust the TargetDate field so the GitHub Project gantt chart matches Trello.

Trello allows issues (cards) to depend on each other, while GitHub Projects lack this feature.

@phoman14

[kelly-sovacool]

related to #7

[phoman14]

@kelly-sovacool
ok i tried something and i don't know how to see if this even makes sense but i used chatGTP to try and create the YAML for this type of action. It definitely needs editing to do the specific action we want but it may be a start
name: Update Issue TargetDate on Comment
Prompt: create YAML for Github action that will update issue TargetDate when specific comment is added to issue
Result:

on:
issue_comment:
types: [created]

jobs:
update-target-date:
runs-on: ubuntu-latest

steps:
  - name: Check comment for target date update
    id: check_comment
    run: |
      COMMENT_BODY="${{ github.event.comment.body }}"
      TARGET_DATE_REGEX="Update TargetDate to (\d{4}-\d{2}-\d{2})"
      
      if [[ $COMMENT_BODY =~ $TARGET_DATE_REGEX ]]; then
        TARGET_DATE="${BASH_REMATCH[1]}"
        echo "TARGET_DATE=$TARGET_DATE" >> $GITHUB_ENV
      else
        echo "No target date update found in comment."
        exit 0
      fi

  - name: Update issue with target date
    if: env.TARGET_DATE
    uses: actions/github-script@v6
    with:
      script: |
        const issueNumber = context.issue.number;
        const targetDate = process.env.TARGET_DATE;
        
        await github.issues.update({
          ...context.repo,
          issue_number: issueNumber,
          labels: ['TargetDate'],
          body: `The TargetDate has been updated to ${targetDate}.`
        });

        await github.issues.createComment({
          ...context.repo,
          issue_number: issueNumber,
          body: `The issue TargetDate has been successfully updated to ${targetDate}.`
        });