Fixing template.

Author: nicolasnoble

packages/grpc-native-core/templates/package.json.template

@@ -31,6 +31,7 @@
       "node-pre-gyp"
     ],
     "dependencies": {
+      "@types/protobufjs": "^5.0.31",
       "lodash.camelcase": "^4.3.0",
       "lodash.clone": "^4.5.0",
       "nan": "^2.13.2",