chore(package): update yeoman-test to version 2.6.0

Closes #15

Author: greenkeeper[bot]

package.json

@@ -38,7 +38,7 @@
     "gulp-standard": "^11.0.0",
     "standard": "^11.0.0",
     "yeoman-assert": "^3.0.0",
-    "yeoman-test": "^1.6.0"
+    "yeoman-test": "^2.6.0"
   },
   "standard": {
     "globals": [],