fix(deps): update dependency unified to v11 (#17)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

package.json

@@ -55,7 +55,7 @@
     "rehype-rewrite": "^3.0.6",
     "rehype-slug": "^6.0.0",
     "remark-gemoji": "^7.0.1",
-    "unified": "^10.1.2",
+    "unified": "^11.0.0",
     "unist-util-visit": "^5.0.0",
     "vfile": "^6.0.0"
   },