fix: move ajv-draft-04 into usage location (#268)

Author: bh2smith

lib/validators/schema.js

@@ -2,7 +2,6 @@
 
 const util = require("../util");
 const { ono } = require("@jsdevtools/ono");
-const AjvDraft4 = require("ajv-draft-04");
 const Ajv = require("ajv/dist/2020");
 const { openapi } = require("@apidevtools/openapi-schemas");
 
@@ -70,6 +69,7 @@ function initializeAjv (draft04 = true) {
   };
 
   if (draft04) {
+    const AjvDraft4 = require("ajv-draft-04");
     return new AjvDraft4(opts);
   }