avoid server.start() deprecation warning

[rnons]

To reproduce, run yarn test serverClass in packages/nice-grpc

yarn run v1.22.22
$ jest serverClass
(node:28544) DeprecationWarning: Calling start() is no longer necessary. It can be safely omitted.
(Use `node --trace-deprecation ...` to show where the warning was created)
 PASS  src/__tests__/serverClass.ts

The DeprecationWarning is from https://github.com/grpc/grpc-node/blob/3c9436be8eb3788173796d4c90d2abe036d0f798/packages/grpc-js/src/server.ts#L1156-L1159

[aikoven]

Thanks!

[aikoven]

Published 📦 nice-grpc@2.1.10