Bump gatsby-plugin-react-helmet from 3.1.20 to 3.1.21

Bumps [gatsby-plugin-react-helmet](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-plugin-react-helmet) from 3.1.20 to 3.1.21.
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-plugin-react-helmet/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/[email protected]/packages/gatsby-plugin-react-helmet)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Author: dependabot-preview[bot]

packages/www/package.json

@@ -15,7 +15,7 @@
     "gatsby-plugin-manifest": "^2.2.36",
     "gatsby-plugin-mdx": "^1.0.67",
     "gatsby-plugin-offline": "^3.0.31",
-    "gatsby-plugin-react-helmet": "^3.1.20",
+    "gatsby-plugin-react-helmet": "^3.1.21",
     "gatsby-plugin-sharp": "^2.3.10",
     "gatsby-plugin-styled-components": "^3.1.17",
     "gatsby-plugin-typescript": "^2.1.26",

yarn.lock

@@ -8521,10 +8521,10 @@ gatsby-plugin-page-creator@^2.1.38:
     lodash "^4.17.15"
     micromatch "^3.1.10"
 
-gatsby-plugin-react-helmet@^3.1.20:
-  version "3.1.20"
-  resolved "https://registry.yarnpkg.com/gatsby-plugin-react-helmet/-/gatsby-plugin-react-helmet-3.1.20.tgz#f6cbf1df71294d96d6241b905bb77abbd386660f"
-  integrity sha512-OouLIrxzo3/j4DvFeq3r2dzYdmNp/0+Gw6IDDm8+vYY9pDMDOrwfj8IJYAb5tfbCpcHw1R5eefM8QVmGK55i3A==
+gatsby-plugin-react-helmet@^3.1.21:
+  version "3.1.21"
+  resolved "https://registry.yarnpkg.com/gatsby-plugin-react-helmet/-/gatsby-plugin-react-helmet-3.1.21.tgz#659f31020295f42d017e2eb03175d73516ab824d"
+  integrity sha512-6LZ2LEYTwqD+ZqyCH55mVpk2xEXbQoCTfijP1W4ZCQsKtpWGJP+vyd6b96FWVyEb2k5LsQ1u+jk4R8xXULSX+w==
   dependencies:
     "@babel/runtime" "^7.7.6"