judge: fix cac load (#1158)

Author: renbaoshuo

packages/hydrojudge/bin/hydrojudge.js

@@ -1,6 +1,6 @@
 #!/usr/bin/env node
 
-const argv = require('cac')().cac().parse();
+const argv = require('cac').cac().parse();
 require('@hydrooj/register');
 
 if (argv.args[0] === 'cache') require('../src/cache')();