explicit update iview

prebuild.js

@@ -1,6 +1,6 @@
 const packageJson = require("./package.json");
 
-if (packageJson.dependencies.iview !== "^3.2.2") {
+if (packageJson.dependencies.iview !== "^3.4.1") {
   console.log("iview 的版本不要轻易升级，一定要充分测试。");
   process.exit(1);
 }