Bump @grpc/grpc-js from 1.8.17 to 1.8.22 in /examples/simple (#191)

Bumps [@grpc/grpc-js](https://github.com/grpc/grpc-node) from 1.8.17 to 1.8.22.

examples/simple/package.json

@@ -2,7 +2,7 @@
   "name": "simple",
   "dependencies": {
     "dgraph-js": "^21.3.1",
-    "@grpc/grpc-js": "1.8.17"
+    "@grpc/grpc-js": "1.8.22"
   },
   "scripts": {
     "example": "node index.js",