chore: upgrade @storybook/addon-a11y from 5.2.5 to 5.2.6

Snyk has created this PR to upgrade @storybook/addon-a11y from 5.2.5 to 5.2.6.

See this package in NPM:
https://www.npmjs.com/package/@storybook/addon-a11y

See this project in Snyk:
https://app.snyk.io/org/stephangerbeth/project/7276c18f-e800-4897-89a5-0e32a5825c22?utm_source=github&utm_medium=upgrade-pr

package.json

@@ -48,7 +48,7 @@
     "@mapbox/stylelint-processor-arbitrary-tags": "^0.2.0",
     "@nuxtjs/sitemap": "^2.0.0",
     "@packtracker/webpack-plugin": "^2.2.0",
-    "@storybook/addon-a11y": "^5.2.5",
+    "@storybook/addon-a11y": "^5.2.6",
     "@storybook/addon-actions": "^5.2.5",
     "@storybook/addon-links": "^5.2.5",
     "@storybook/addon-viewport": "^5.2.5",