chore(package): update dependencies

Author: greenkeeper[bot]

package.json

@@ -41,15 +41,15 @@
   },
   "devDependencies": {
     "@thebespokepixel/cordial": "^0.17.11",
-    "ava": "^0.17.0",
+    "ava": "^0.25.0",
     "babel-plugin-external-helpers": "^6.8.0",
-    "documentation": "^4.0.0-beta15",
+    "documentation": "^8.0.0",
     "documentation-theme-bespoke": "^0.3.5",
-    "codeclimate-test-reporter": "^0.4.0",
+    "codeclimate-test-reporter": "^0.5.0",
     "greenkeeper-postpublish": "^1.0.1",
     "gulp": "github:gulpjs/gulp#4.0",
-    "nyc": "^10.0.0",
-    "xo": "^0.17.0"
+    "nyc": "^12.0.2",
+    "xo": "^0.21.1"
   },
   "engines": {
     "node": ">=4.0 <9.0"