Remove AutoMerge Github Action (#273)

Instead, we will be trying out the official Microsoft bot https://docs.opensource.microsoft.com/tools/fabricbot/index.html

.github/workflows/automerge.yml

@@ -1,29 +0,0 @@
-name: automerge
-on:
-  pull_request:
-    types:
-      - labeled
-      - unlabeled
-      - synchronize
-      - opened
-      - edited
-      - ready_for_review
-      - reopened
-      - unlocked
-  pull_request_review:
-    types:
-      - submitted
-  check_suite:
-    types:
-      - completed
-  status: {}
-jobs:
-  automerge:
-    runs-on: ubuntu-latest
-    steps:
-      - name: automerge
-        uses: "pascalgn/automerge-action@v0.11.0"
-        env:
-          GITHUB_TOKEN: "${{ secrets.AUTOMERGE_GITHUB_PAT }}"
-          MERGE_METHOD: "squash"
-          MERGE_COMMIT_MESSAGE: "pull-request-title"