workflow: use merge --squash instead of rebase

.gitea/workflows/update-flake.yaml

@@ -16,10 +16,29 @@ jobs:
           fetch-depth: 0
           ref: flake-updates
 
-      - name: Fetch latest changes and reset branch
+      - name: Git config
+        shell: bash
         run: |
-          git fetch origin master
-          git reset --hard origin/master
+          git config user.name "Gitea Actions"
+          git config user.email "actions@gitea.local"
+
+      - name: Merge master branch
+        shell: bash
+        run: |
+            commits_ahead=$(git rev-list --count HEAD..origin/master)
+            echo "Commits ahead: $commits_ahead"
+            git log --oneline -5
+            echo "----------"
+            git log --oneline -5 origin/master
+
+            if [ $commits_ahead -ne 0 ]
+            then
+              git fetch origin
+              git merge -X theirs --squash origin/master
+              git commit -m "Merge master branch squashed $(date -I)"
+            else
+              echo "Merge not necessary"
+            fi
 
       - name: Set up Nix
         uses: cachix/install-nix-action@v31
@@ -30,10 +49,8 @@ jobs:
       - name: Commit and push changes
         shell: bash
         run: |
-          git config user.name "Gitea Actions"
-          git config user.email "actions@gitea.local"
           git add flake.lock
-          if git diff --cached --quiet; then
+          if git diff --quiet; then
             echo "No changes to commit."
           else
             git commit -m "Update flake.lock $(date -I)"