chore(deps): bump prismjs from 1.20.0 to 1.21.0

Bumps [prismjs](https://github.com/PrismJS/prism) from 1.20.0 to 1.21.0.
- [Release notes](https://github.com/PrismJS/prism/releases)
- [Changelog](https://github.com/PrismJS/prism/blob/master/CHANGELOG.md)
- [Commits](https://github.com/PrismJS/prism/compare/v1.20.0...v1.21.0)

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -75,7 +75,7 @@
     "netlify-cms-app": "^2.12.19",
     "node-sass": "^4.14.1",
     "normalize-scss": "^7.0.1",
-    "prismjs": "^1.20.0",
+    "prismjs": "^1.21.0",
     "react": "^16.13.1",
     "react-disqus-comments": "^1.4.0",
     "react-dom": "^16.13.1",

yarn.lock

@@ -15267,10 +15267,10 @@ pretty-format@^26.2.0:
     ansi-styles "^4.0.0"
     react-is "^16.12.0"
 
-prismjs@^1.20.0:
-  version "1.20.0"
-  resolved "https://registry.yarnpkg.com/prismjs/-/prismjs-1.20.0.tgz#9b685fc480a3514ee7198eac6a3bf5024319ff03"
-  integrity sha512-AEDjSrVNkynnw6A+B1DsFkd6AVdTnp+/WoUixFRULlCLZVRZlVQMVWio/16jv7G1FscUxQxOQhWwApgbnxr6kQ==
+prismjs@^1.21.0:
+  version "1.21.0"
+  resolved "https://registry.yarnpkg.com/prismjs/-/prismjs-1.21.0.tgz#36c086ec36b45319ec4218ee164c110f9fc015a3"
+  integrity sha512-uGdSIu1nk3kej2iZsLyDoJ7e9bnPzIgY0naW/HdknGj61zScaprVEVGHrPoXqI+M9sP0NDnTK2jpkvmldpuqDw==
   optionalDependencies:
     clipboard "^2.0.0"