Update gatsby monorepo (#1274)

Co-authored-by: Renovate Bot <bot@renovateapp.com>

package.json

@@ -59,7 +59,7 @@
     "eslint-plugin-mdx": "1.8.2",
     "eslint-plugin-prettier": "3.1.4",
     "eslint-plugin-react": "7.20.6",
-    "gatsby": "2.24.62",
+    "gatsby": "2.25.3",
     "hast-util-select": "4.0.0",
     "husky": "4.3.0",
     "jest": "26.6.3",

packages/gatsby-theme-mdx/package.json

@@ -31,17 +31,17 @@
     "@rebass/emotion": "3.2.0",
     "@theme-ui/components": "0.3.1",
     "@theme-ui/preset-system": "0.3.0",
-    "gatsby": "2.24.62",
-    "gatsby-plugin-catch-links": "2.3.12",
+    "gatsby": "2.25.3",
+    "gatsby-plugin-catch-links": "2.3.15",
     "gatsby-plugin-compile-es6-packages": "2.1.0",
-    "gatsby-plugin-emotion": "4.3.11",
+    "gatsby-plugin-emotion": "4.3.15",
     "gatsby-plugin-fathom": "1.3.0",
     "gatsby-plugin-google-fonts": "1.0.1",
-    "gatsby-plugin-mdx": "1.2.40",
-    "gatsby-plugin-page-creator": "2.3.28",
-    "gatsby-plugin-react-helmet": "3.3.11",
+    "gatsby-plugin-mdx": "1.3.1",
+    "gatsby-plugin-page-creator": "2.3.35",
+    "gatsby-plugin-react-helmet": "3.3.14",
     "gatsby-plugin-theme-ui": "0.3.0",
-    "gatsby-source-filesystem": "2.3.30",
+    "gatsby-source-filesystem": "2.4.2",
     "is-absolute-url": "3.0.3",
     "lodash.flatten": "4.4.0",
     "prism-react-renderer": "1.1.1",