fix: add missing shiki dependency to package.json

Author: NoOne7135

custom/package.json

@@ -22,6 +22,7 @@
     "dompurify": "^3.3.3",
     "katex": "^0.16.45",
     "marked": "^18.0.0",
+    "shiki": "^4.0.2",
     "vega-embed": "^7.1.0",
     "voice-activity-detection": "^0.0.5"
   }