Update dependency c8 to v9 (#554)

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

package.json

@@ -27,7 +27,7 @@
   },
   "devDependencies": {
     "ava": "^6.0.0",
-    "c8": "^8.0.0",
+    "c8": "^9.0.0",
     "eslint": "^8.27.0",
     "eslint-config-problems": "^8.0.0",
     "eslint-plugin-prettier": "^5.0.0",