fix prod build date

prebuild.js

@@ -8,7 +8,7 @@ if (packageJson.dependencies.iview !== "^3.5.4") {
 console.log("> prebuild");
 console.log("> prebuild create .env.*.local");
 
-const buildDate = require("moment")().format("YYYY-MM-DD HH:mm:SS");
+const buildDate = require("moment")().format("YYYY-MM-DD HH:mm:ss");
 console.log("  构建日期为 " + buildDate);
 
 const revision = require("child_process")