Simplify merge strategy for staging

.github/workflows/merge-main-into-staging.yaml

@@ -3,7 +3,7 @@ name: Merge main into staging
 on:
   push:
     branches:
-      - main
+      - simplify-merge-strategy
 
 permissions:
   contents: write
@@ -19,6 +19,7 @@ jobs:
         uses: actions/checkout@v3
         with:
           ref: staging
+          fetch-depth: 0
 
       - name: Configure git
         run: |
@@ -27,8 +28,7 @@ jobs:
 
       - name: Merge in main branch
         run: |
-          git fetch origin main:main
-          git merge main --no-ff --allow-unrelated-histories --strategy-option theirs -m "Merging latest changes from main into staging"
+          git merge --no-ff origin/main
 
       - name: Create pull request
         id: pr-number