refactor: pinning dependency to prevent JS error (pattern-lab#1390)

Author: mfranzke

packages/uikit-workshop/package.json

@@ -80,7 +80,7 @@
     "preact-render-to-string": "^4.1.0",
     "preload-webpack-plugin": "^3.0.0-beta.3",
     "pretty": "^2.0.0",
-    "prismjs": "^1.15.0",
+    "prismjs": "1.23.0",
     "pwa-helpers": "^0.9.1",
     "react-autosuggest": "^9.4.2",
     "react-dom": "^16.8.6",