Update grpc to 1.16.1 to support node 11

[sunnylqm]

Need to update grpc dependency to 1.16.1 to support node 11 according to grpc/grpc-node#594 (comment)

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[sunnylqm]

Just signed cla

[googlebot]

CLAs look good, thanks!

[mikelehen]

Thanks! Could you also update it in packages/functions and then re-run yarn from the root to update our yarn.lock file?

[LiteSoul]

Patiently waiting for Node 11 support 🙏

[mikelehen]

LGTM. @Feiyang1 feel free to merge.