feat(ci): add merge conflict labeler workflow

.github/workflows/conflict_labeler.yml

@@ -0,0 +1,25 @@
+name: Merge Conflict Labeler
+
+on:
+  push:
+    branches:
+      - develop
+  pull_request_target:
+    branches:
+      - develop
+    types: [synchronize]
+
+jobs:
+  label:
+    name: Labeling
+    runs-on: ubuntu-latest
+    if: ${{ github.repository == 'Radarr/Radarr' }}
+    permissions:
+      contents: read
+      pull-requests: write
+    steps:
+      - name: Apply label
+        uses: eps1lon/actions-label-merge-conflict@v3
+        with:
+          dirtyLabel: 'merge-conflict'
+          repoToken: '${{ secrets.GITHUB_TOKEN }}'