fix(contentful): reenable support for gif images (#31986) (#32029)

(cherry picked from commit a30aa0b)

Co-authored-by: Benedikt Rötsch <axe312ger@users.noreply.github.com>

Author: GatsbyJS Bot

packages/gatsby-source-contentful/src/extend-node-type.js

@@ -32,7 +32,8 @@ const {
 // cache is more likely to go stale than the images (which never go stale)
 // Note that the same image might be requested multiple times in the same run
 
-const validImageFormats = new Set([`jpg`, `png`, `webp`])
+// Supported Image Formats from https://www.contentful.com/developers/docs/references/images-api/#/reference/changing-formats/image-format
+const validImageFormats = new Set([`jpg`, `png`, `webp`, `gif`])
 
 if (process.env.GATSBY_REMOTE_CACHE) {
   console.warn(