Limit default labelling to opened, reopened and synchronize PR

Also remove "Ready to merge" in case PR is changed / fresh

.github/workflows/pr-auto-labeler.yml

@@ -5,9 +5,23 @@ run-name: 'Set labels - PR #${{ github.event.pull_request.number }} ("${{ github
 #
 
 on:
-  - pull_request_target
+  pull_request:
+    types: [opened, reopened, synchronize]
 
 jobs:
+  label-remove:
+    permissions:
+      contents: read # for pascalgn/size-label-action to determine modified files
+      pull-requests: write # for pascalgn/size-label-action to add labels to PRs
+    name: "Remove Ready to merge"
+    runs-on: ubuntu-latest
+    steps:
+      - uses: PauMAVA/add-remove-label-action@v1.0.3
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          add: ""
+          remove: "Ready to merge"
+
   label-category:
     permissions:
       contents: read # for actions/labeler to determine modified files