Fix workflow syntax

Author: agners

.github/workflows/dependency-update.yaml

@@ -40,7 +40,7 @@ jobs:
 
       # Create Pull Request only if there were changes
       - name: Create Pull Request
-        if: ${{ steps.update-submodule.outputs.empty != "true" }}
+        if: ${{ steps.update-submodule.outputs.empty != true }}
         uses: peter-evans/create-pull-request@v6
         with:
           commit-message: Update Matter SDK to `${{ steps.update-submodule.outputs.short_hash }}`