fix(contentful): migrate to latest rich text helper packages

Author: axe312ger

packages/gatsby-source-contentful/package.json

@@ -8,8 +8,8 @@
   },
   "dependencies": {
     "@babel/runtime": "^7.15.4",
-    "@contentful/rich-text-react-renderer": "15.5.1",
-    "@contentful/rich-text-types": "15.5.1",
+    "@contentful/rich-text-react-renderer": "^15.6.2",
+    "@contentful/rich-text-types": "^15.6.2",
     "@hapi/joi": "^15.1.1",
     "@vercel/fetch-retry": "^5.0.3",
     "axios": "^0.21.1",