Update ava to the latest version 🚀 (#487)

* chore(package): update ava to version 0.20.0

* Add greenkeeper-lockfile

* Update yarn.lock

.travis.yml

@@ -14,11 +14,19 @@ matrix:
     - node_js: "lts/*"
       env: JOB=lint
 
+before_install:
+  - yarn global add greenkeeper-lockfile@1
+
 before_script:
+  - greenkeeper-lockfile-update
   - 'if [ "$JOB" = "test" ]; then BABEL_ENV=test yarn run build; fi'
 
 script:
   - 'if [ "$JOB" = "test" ]; then yarn test-only; fi'
   - 'if [ "$JOB" = "lint" ]; then yarn run lint; fi'
+
+after_script:
+  - greenkeeper-lockfile-upload
+
 after_success:
   - bash <(curl -s https://codecov.io/bash) -f coverage/coverage-final.json

package.json

@@ -19,7 +19,7 @@
     "webpack": "2 || 3"
   },
   "devDependencies": {
-    "ava": "^0.19.0",
+    "ava": "^0.20.0",
     "babel-cli": "^6.18.0",
     "babel-core": "^6.0.0",
     "babel-eslint": "^7.1.0",