Bump prismjs from 1.19.0 to 1.21.0

Bumps [prismjs](https://github.com/PrismJS/prism) from 1.19.0 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/v1.19.0...v1.21.0)

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

package-lock.json

@@ -1223,9 +1223,9 @@
       "dev": true
     },
     "prismjs": {
-      "version": "1.19.0",
-      "resolved": "https://registry.npmjs.org/prismjs/-/prismjs-1.19.0.tgz",
-      "integrity": "sha512-IVFtbW9mCWm9eOIaEkNyo2Vl4NnEifis2GQ7/MLRG5TQe6t+4Sj9J5QWI9i3v+SS43uZBlCAOn+zYTVYQcPXJw==",
+      "version": "1.21.0",
+      "resolved": "https://registry.npmjs.org/prismjs/-/prismjs-1.21.0.tgz",
+      "integrity": "sha512-uGdSIu1nk3kej2iZsLyDoJ7e9bnPzIgY0naW/HdknGj61zScaprVEVGHrPoXqI+M9sP0NDnTK2jpkvmldpuqDw==",
       "dev": true,
       "requires": {
         "clipboard": "^2.0.0"

package.json

@@ -32,7 +32,7 @@
     "loading-cli": "1.1.0",
     "marked": "1.1.1",
     "path": "0.12.7",
-    "prismjs": "1.19.0",
+    "prismjs": "1.21.0",
     "sitemap-generator": "8.4.2",
     "sqlite3": "4.1.1",
     "stylus": "0.54.7",