chore(deps): update dependency prettier to ^2.8.7

Author: renovate[bot]

package.json

@@ -7,7 +7,7 @@
   "devDependencies": {
     "@semantic-release/exec": "^5.0.0",
     "@sourcegraph/prettierrc": "^3.0.3",
-    "prettier": "^2.3.1",
+    "prettier": "^2.8.7",
     "semantic-release": "^17.0.8"
   }
 }