Update dependency c8 to v11

Author: renovate[bot]

package.json

@@ -36,7 +36,7 @@
   "homepage": "https://theme-next.js.org",
   "devDependencies": {
     "@next-theme/eslint-config": "0.0.5",
-    "c8": "10.1.3",
+    "c8": "11.0.0",
     "chai": "6.2.2",
     "eslint": "9.39.2",
     "hexo": "8.1.1",