chore(deps): update dependency @types/mocha to v8 (#504)

Author: renovate-bot

packages/google-privacy-dlp/package.json

@@ -47,7 +47,7 @@
     "protobufjs": "^6.8.0"
   },
   "devDependencies": {
-    "@types/mocha": "^7.0.0",
+    "@types/mocha": "^8.0.0",
     "@types/node": "^12.0.0",
     "@types/sinon": "^9.0.0",
     "c8": "^7.0.0",