chore(package): update @storybook/addon-a11y to version 5.0.0

Closes #84

Author: greenkeeper[bot]

package.json

@@ -56,7 +56,7 @@
     "@dollarshaveclub/e2e": "^1.1.3",
     "@dollarshaveclub/monitor": "^1.7.3",
     "@jongleberry/json-check": "^1.0.0",
-    "@storybook/addon-a11y": "^4.0.0-alpha.2",
+    "@storybook/addon-a11y": "^5.0.0",
     "@storybook/addon-actions": "^5.0.0",
     "@storybook/addon-links": "^5.0.0",
     "@storybook/addon-storyshots": "^5.0.0",