outdated: drop the error message

PR-URL: #14013
Credit: @zkat
Reviewed-By: @iarna

lib/outdated.js

@@ -111,12 +111,8 @@ function outdated (args, silent, cb) {
         }
         output(table(outTable, tableOpts))
       }
-      var msg = [
-        'The outdated dependencies were found. Please make sure',
-        'the versions in node_module, or look over package.json',
-        'to use the most suitable semver range.'
-      ].join('\n')
-      cb(msg, list.map(function (item) { return [item[0].parent.path].concat(item.slice(1, 7)) }))
+      process.exitCode = list.length
+      cb(null, list.map(function (item) { return [item[0].parent.path].concat(item.slice(1, 7)) }))
     })
   }))
 }