test: use regex to test the error message

This is to fix the circle ci test failure.

https://circleci.com/gh/vuejs/jsx/77

Such errors never occurred on my local machine. So I have to hack it.

Author: haoqunjiang

packages/babel-plugin-transform-vue-jsx/test/snapshot.js

@@ -353,7 +353,7 @@ test('JSXElement attribute value throws error', t =>
         resolve()
       })
       .catch(e => {
-        t.is(e.message, 'getAttributes (attribute value): JSXElement is not supported')
+        t.regex(e.message, /getAttributes \(attribute value\): JSXElement is not supported/)
         resolve()
       })
   }))