Update dependency gatsby-plugin-sharp to v4 [SECURITY]

Author: renovate[bot]

Diff for: package.json

@@ -28,7 +28,7 @@
     "gatsby-plugin-react-helmet": "4.8.0",
     "gatsby-plugin-robots-txt": "1.6.8",
     "gatsby-plugin-sass": "4.8.0",
-    "gatsby-plugin-sharp": "3.8.0",
+    "gatsby-plugin-sharp": "4.25.1",
     "gatsby-plugin-sitemap": "4.4.0",
     "gatsby-remark-copy-linked-files": "4.5.0",
     "gatsby-remark-images": "5.5.0",