add: GitHub authentication

src/auth.ts

@@ -0,0 +1,10 @@
+import payloadConfig from "@payload-config";
+import NextAuth from "next-auth";
+import { withPayload } from "payload-authjs";
+import { authConfig } from "./auth.config";
+
+export const { handlers, signIn, signOut, auth } = NextAuth(
+  withPayload(authConfig, {
+    payloadConfig,
+  }),
+);