fix(deps): update dependency google-gax to v2.29.6 (#1489)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [google-gax](https://github.com/googleapis/gax-nodejs) | [`2.29.5` -> `2.29.6`](https://renovatebot.com/diffs/npm/google-gax/2.29.5/2.29.6) | [![age](https://badges.renovateapi.com/packages/npm/google-gax/2.29.6/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/npm/google-gax/2.29.6/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/npm/google-gax/2.29.6/compatibility-slim/2.29.5)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/npm/google-gax/2.29.6/confidence-slim/2.29.5)](https://docs.renovatebot.com/merge-confidence/) |

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### Release Notes

<details>
<summary>googleapis/gax-nodejs</summary>

### [`v2.29.6`](https://github.com/googleapis/gax-nodejs/blob/HEAD/CHANGELOG.md#&#8203;2296-httpsgithubcomgoogleapisgax-nodejscomparev2295v2296-2022-02-10)

[Compare Source](https://github.com/googleapis/gax-nodejs/compare/v2.29.5...v2.29.6)

</details>

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package.json

@@ -58,7 +58,7 @@
     "arrify": "^2.0.0",
     "extend": "^3.0.2",
     "google-auth-library": "^7.0.0",
-    "google-gax": "2.29.5",
+    "google-gax": "2.29.6",
     "is-stream-ended": "^0.1.4",
     "lodash.snakecase": "^4.1.1",
     "p-defer": "^3.0.0"