chore: Register serverless as peer dependency

It's to ensure only compatible versions or Framework are used together with a plugin

Author: medikoo

package.json

@@ -67,6 +67,9 @@
     "sha256-file": "1.0.0",
     "shell-quote": "^1.7.2"
   },
+  "peerDependencies": {
+    "serverless": "^1.34 || 2"
+  },
   "eslintConfig": {
     "extends": "eslint:recommended",
     "env": {