build: bump "prettier" Node.js dep

Author: PaulRBerg

package.json

@@ -10,7 +10,7 @@
     "url": "https://github.com/PaulRBerg/prb-contracts/issues"
   },
   "devDependencies": {
-    "prettier": "^2.8.3",
+    "prettier": "^2.8.7",
     "solhint": "^3.3.8"
   },
   "files": [