chore(package): update textlint-tester to version 2.0.0

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -41,6 +41,6 @@
     "npm-run-all": "^2.1.2",
     "power-assert": "^1.4.1",
     "textlint": "^6.11.1",
-    "textlint-tester": "^1.2.0"
+    "textlint-tester": "^2.0.0"
   }
 }