Update dependency c8 to v12

Author: renovate[bot]

package.json

@@ -31,7 +31,7 @@
   },
   "devDependencies": {
     "ava": "^3.1.0",
-    "c8": "^10.0.0",
+    "c8": "^12.0.0",
     "coveralls": "^3.0.0",
     "eslint": "^9.22.0",
     "eslint-config-problems": "9.0.0",