Bump prismjs from 1.17.1 to 1.21.0

Bumps [prismjs](https://github.com/PrismJS/prism) from 1.17.1 to 1.21.0.
- [Release notes](https://github.com/PrismJS/prism/releases)
- [Changelog](https://github.com/PrismJS/prism/blob/master/CHANGELOG.md)
- [Commits](PrismJS/prism@v1.17.1...v1.21.0)

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

package.json

@@ -71,7 +71,7 @@
     "mocha": "^5.2.0",
     "mocha-lcov-reporter": "^1.3.0",
     "popper.js": "^1.14.3",
-    "prismjs": "^1.14.0",
+    "prismjs": "^1.21.0",
     "prop-types": "^15.6.2",
     "querystring": "^0.2.0",
     "react-clipboard.js": "^2.0.0",

yarn.lock

@@ -7707,10 +7707,10 @@ pretty-format@^20.0.3:
     ansi-regex "^2.1.1"
     ansi-styles "^3.0.0"
 
-prismjs@^1.14.0:
-  version "1.17.1"
-  resolved "https://registry.yarnpkg.com/prismjs/-/prismjs-1.17.1.tgz#e669fcbd4cdd873c35102881c33b14d0d68519be"
-  integrity sha512-PrEDJAFdUGbOP6xK/UsfkC5ghJsPJviKgnQOoxaDbBjwc8op68Quupwt1DeAFoG8GImPhiKXAvvsH7wDSLsu1Q==
+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"