fix: examples/using-gatsby-image/package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-GATSBYPLUGINSHARP-5425803

Author: snyk-bot

examples/using-gatsby-image/package.json

@@ -11,7 +11,7 @@
     "gatsby-image": "^2.0.19",
     "gatsby-plugin-emotion": "^4.0.6",
     "gatsby-plugin-netlify": "^2.0.3",
-    "gatsby-plugin-sharp": "^2.0.11",
+    "gatsby-plugin-sharp": "^4.25.1",
     "gatsby-plugin-typography": "^2.2.1",
     "gatsby-source-filesystem": "^2.0.7",
     "gatsby-transformer-sharp": "^2.1.7",