chore(deps): update dependency gatsby-plugin-sass to v6

Author: renovate[bot]

www/package.json

@@ -18,7 +18,7 @@
     "emotion": "^10.0.27",
     "gatsby": "^2.32.11",
     "gatsby-plugin-astroturf": "^0.2.1",
-    "gatsby-plugin-sass": "^2.8.0",
+    "gatsby-plugin-sass": "^6.12.2",
     "lodash": "^4.17.21",
     "prop-types": "^15.7.2",
     "react": "^16.14.0",