add publish action

.github/workflows/publish.yml

@@ -0,0 +1,17 @@
+name: Gatsby Publish
+
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: enriikke/gatsby-gh-pages-action@v2
+        with:
+          access-token: ${{ secrets.PAT_GITHUB }}
+          deploy-branch: gh-pages
+          gatsby-args: --prefix-paths