deps: make "only" package inside (#1824)

closes https://github.com/koajs/koa/issues/1802

package-lock.json

@@ -24,7 +24,6 @@
         "http-errors": "^1.6.3",
         "koa-compose": "^4.1.0",
         "on-finished": "^2.3.0",
-        "only": "~0.0.2",
         "parseurl": "^1.3.2",
         "statuses": "^1.5.0",
         "type-is": "^1.6.16",
@@ -5380,11 +5379,6 @@
         "url": "https://github.com/sponsors/sindresorhus"
       }
     },
-    "node_modules/only": {
-      "version": "0.0.2",
-      "resolved": "https://registry.npmjs.org/only/-/only-0.0.2.tgz",
-      "integrity": "sha1-Kv3oTQPlC5qO3EROMGEKcCle37Q="
-    },
     "node_modules/optionator": {
       "version": "0.9.3",
       "resolved": "https://registry.npmjs.org/optionator/-/optionator-0.9.3.tgz",