Fix broken Github workflow

Author: xavierfoucrier

.github/workflows/deploy-docs.yml

@@ -21,7 +21,7 @@ jobs:
         run: npm run build
 
       - name: Deploy the documentation
-        uses: JamesIves/github-pages-deploy-action@master
+        uses: JamesIves/github-pages-deploy-action@4.1.1
         env:
           BASE_BRANCH: source
           BRANCH: master