Update gh-pages.yml (AtsushiSakai#758)

Author: AtsushiSakai

.github/workflows/gh-pages.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Setup python
-      uses: actions/setup-python@v2
+      uses: actions/setup-python@v3
     - name: Checkout
       uses: actions/checkout@master
       with:
@@ -26,4 +26,4 @@ jobs:
       uses: ad-m/github-push-action@master
       with:
         github_token: ${{ secrets.GITHUB_TOKEN }}
-        branch: gh-pages
+        branch: gh-pages