chore(package): update @storybook/addon-knobs to version 5.3.18

Closes #23

Author: greenkeeper[bot]

package.json

@@ -24,7 +24,7 @@
     "@babel/preset-react": "^7.0.0",
     "@babel/register": "^7.0.0",
     "@storybook/addon-actions": "^5.3.18",
-    "@storybook/addon-knobs": "^4.0.2",
+    "@storybook/addon-knobs": "^5.3.18",
     "@storybook/addon-storyshots": "^4.0.2",
     "@storybook/addon-storyshots-puppeteer": "^4.0.2",
     "@storybook/addon-viewport": "^4.0.2",