fix: Improve CI script to update version

Author: nickevansuk

.github/workflows/create-data-model-pr.yaml

@@ -41,10 +41,12 @@ jobs:
         run: dotnet add package OpenActive.NET
         working-directory: ./OpenActive.DatasetSite.NET/
 
-      - name: Do not commit version bumps of the generator
-        run: git checkout package.json package-lock.json
+      - name: Do not commit version bumps of the generator unless something else has been updated
+        run:
+          git stash push package.json package-lock.json
+          if [ -z "$(git status --porcelain)" ]; then echo "No changes"; else git stash apply; fi
         working-directory: ./OpenActive.DatasetSite.NET.Generator/
-      
+
       - name: Create Pull Request
         id: cpr
         uses: peter-evans/create-pull-request@v3