fix: upgrade markdown-it-table-of-contents from 0.4.4 to 0.6.0

Snyk has created this PR to upgrade markdown-it-table-of-contents from 0.4.4 to 0.6.0.

See this package in npm:
https://www.npmjs.com/package/markdown-it-table-of-contents

See this project in Snyk:
https://app.snyk.io/org/sammytezzy/project/966f2c8d-e98f-4366-9980-1b3b4b9e9513?utm_source=github&utm_medium=referral&page=upgrade-pr

package.json

@@ -349,7 +349,7 @@
     "markdown-it-mathjax": "^2.0.0",
     "markdown-it-sub": "^1.0.0",
     "markdown-it-sup": "^1.0.0",
-    "markdown-it-table-of-contents": "^0.4.4",
+    "markdown-it-table-of-contents": "^0.6.0",
     "mathjax": "^3.0.1",
     "mathjax-full": "^3.0.1",
     "string": "git+ssh://git@github.com/hackmdio/string.js.git#a68176b3d",