Add ssr as main package

Author: janniks

package.json

@@ -3,7 +3,7 @@
   "version": "1.3.4",
   "description": "A Vue renderer for Notion pages",
   "repository": "github:janniks/vue-notion",
-  "main": "dist/esm.js",
+  "main": "dist/ssr.js",
   "browser": "dist/esm.js",
   "module": "dist/esm.js",
   "unpkg": "dist/min.js",