add iview upgrade hint

prebuild.js

@@ -1,3 +1,12 @@
+const packageJson = require("./package.json");
+
+if (packageJson.dependencies.iview !== "^3.1.2") {
+  console.log(
+    "iview 的版本不要轻易升级，一定要充分测试。曾经尝试升级到3.2.2后发现progressbar有问题。"
+  );
+  process.exit(1);
+}
+
 console.log("> prebuild");
 console.log("> prebuild create .env.production.local");