bugfix(microservices) remove credentials from options to fix TypeError
bugfix(microservices) remove credentials from options to fix TypeError

I use to have the following exception:
```
(node:19) UnhandledPromiseRejectionWarning: TypeError: Channel options must be an object with string keys and integer or string values
```
I was passing down a credential object to the options like this:
```
const credentials = grpc.credentials.createSsl(
  readFileSync('/srv/certs/rootCA.pem'),
  readFileSync('/srv/certs/server.key'),
  readFileSync('/srv/certs/server.crt')
  );

// later
  @Client({
    transport: Transport.GRPC,
    options: {
      url: 'ms-proxy:50051',
      package: 'hero',
      protoPath: join(__dirname, '..', 'proto/hero.proto'),
      credentials,
    },
  })
``

kamilmysliwiec/nest,kamilmysliwiec/nest