fix packages error

packages/remark-growi-directive/package.json

@@ -1,4 +1,3 @@
-
 {
   "name": "@growi/remark-growi-directive",
   "version": "0.9.0",
@@ -44,7 +43,7 @@
     "uvu": "^0.5.0"
   },
   "devDependencies": {
-    "c8": "^7.0.0",
+    "c8": "^8.0.0",
     "html-void-elements": "^2.0.0",
     "is-hidden": "^2.0.0",
     "mdast-util-from-markdown": "^2.0.1",