chore: Remove unused workflow

.github/workflows/completed_issue_comment.yaml

@@ -1,24 +0,0 @@
-name: Completed Issue Comment
-
-on:
-  issues:
-    types: [labeled]
-
-jobs:
-  completed_issue_comment:
-    if: github.event.label.name == 'status:completed'
-    runs-on: ubuntu-latest
-    env:
-        GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-    steps:
-      - run: |
-          gh issue comment ${{ github.event.issue.number }} --body "$(cat <<EOF
-          Thank you so much for reporting this issue and helping us improve FluffyChat! 💬💖
-
-          This project is built and maintained by volunteers in their free time.
-          If you enjoyed using FluffyChat and want to support the people behind it,
-          you can say thanks by buying us a coffee or chipping in:
-          ☕ https://ko-fi.com/krille  
-          💜 https://liberapay.com/KrilleChritzelius
-          EOF
-          )"