tocのコードをちゃんとした

bun.lock

@@ -1,10 +1,11 @@
 {
-  "lockfileVersion": 0,
+  "lockfileVersion": 1,
   "workspaces": {
     "": {
       "dependencies": {
         "@twemoji/parser": "^15.1.1",
         "github-slugger": "^2.0.0",
+        "mdast-util-to-string": "^4.0.0",
         "rehype-external-links": "^3.0.0",
         "rehype-github-alert": "^1.0.0",
         "rehype-highlight": "^7.0.1",
@@ -16,6 +17,7 @@
         "remark-gfm": "^4.0.0",
         "remark-math": "^6.0.0",
         "remark-rehype": "^11.1.1",
+        "unist-util-visit-parents": "^6.0.1",
         "yaml": "^2.6.1",
       },
       "devDependencies": {