Only deploy documentation on main (#1055)

Author: Kludex

.github/workflows/ci.yml

@@ -228,9 +228,9 @@ jobs:
           allowed-skips: test-live
 
   deploy-docs:
-    if: "success() && github.ref == 'refs/heads/main'"
-    runs-on: ubuntu-latest
     needs: [check]
+    if: "success() && startsWith(github.ref, 'refs/tags/')"
+    runs-on: ubuntu-latest
     environment:
       name: deploy-docs
       url: https://ai.pydantic.dev