Upgrade PostGraphile

Author: benjie

package.json

@@ -36,7 +36,7 @@
     "apollo-link": "^1.2.3",
     "gatsby-source-graphql": "^2.0.5",
     "pg": "^7.6.0",
-    "postgraphile": "^4.1.0-rc.0"
+    "postgraphile": "^4.4.0"
   },
   "peerDependencies": {
     "graphql": "^0.13.x | ^14.0.0"