Update dependency gatsby-transformer-remark to v5 [SECURITY]

Author: renovate[bot]

packages/website/package.json

@@ -38,7 +38,7 @@
     "gatsby-remark-responsive-iframe": "^2.2.0",
     "gatsby-source-filesystem": "^2.1.0",
     "gatsby-transformer-json": "^2.2.0",
-    "gatsby-transformer-remark": "^2.5.0",
+    "gatsby-transformer-remark": "^5.0.0",
     "lodash": "^4.17.4",
     "lodash-webpack-plugin": "^0.11.4",
     "prismjs": "^1.16.0",