fix(deps): Update dependency @grpc/grpc-js to v1.9.4 (#18)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [@grpc/grpc-js](https://grpc.io/) ([source](https://togithub.com/grpc/grpc-node)) | devDependencies | patch | [`1.9.2` -> `1.9.4`](https://renovatebot.com/diffs/npm/@grpc%2fgrpc-js/1.9.2/1.9.4) |

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### Release Notes

<details>
<summary>grpc/grpc-node (@&#8203;grpc/grpc-js)</summary>

### [`v1.9.4`](https://togithub.com/grpc/grpc-node/releases/tag/%40grpc/grpc-js%401.9.4): @&#8203;grpc/grpc-js 1.9.4

[Compare Source](https://togithub.com/grpc/grpc-node/compare/@grpc/[email protected]...@grpc/[email protected])

-   Fix a bug that could cause a client to sometimes incorrectly hold the process open when no longer in use ([#&#8203;2586](https://togithub.com/grpc/grpc-node/issues/2586))

### [`v1.9.3`](https://togithub.com/grpc/grpc-node/releases/tag/%40grpc/grpc-js%401.9.3): @&#8203;grpc/grpc-js 1.9.3

[Compare Source](https://togithub.com/grpc/grpc-node/compare/@grpc/[email protected]...@grpc/[email protected])

-   Make a few improvements to DNS resolving timing ([#&#8203;2571](https://togithub.com/grpc/grpc-node/issues/2571))

Experimental changes:

-   Added `grpc.experimental.BackoffTimeout#getEndTime`

</details>

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Author: cq-bot