fix(deps): update dependency @mdit/plugin-sub to v0.23.1

Author: renovate[bot]

packages/server/package.json

@@ -22,7 +22,7 @@
     "@koa/cors": "^5.0.0",
     "@mdit/plugin-katex": "0.23.4-cjs.0",
     "@mdit/plugin-mathjax": "0.23.4-cjs.0",
-    "@mdit/plugin-sub": "0.22.5-cjs.0",
+    "@mdit/plugin-sub": "0.23.1",
     "@mdit/plugin-sup": "0.22.5-cjs.0",
     "akismet": "^2.0.7",
     "deta": "^2.0.0",