chore(deps): update dependency google-cloud-bigquery to v2.23.3 (#866)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [google-cloud-bigquery](https://togithub.com/googleapis/python-bigquery) | `==2.23.2` -> `==2.23.3` | [![age](https://badges.renovateapi.com/packages/pypi/google-cloud-bigquery/2.23.3/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/pypi/google-cloud-bigquery/2.23.3/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/pypi/google-cloud-bigquery/2.23.3/compatibility-slim/2.23.2)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/pypi/google-cloud-bigquery/2.23.3/confidence-slim/2.23.2)](https://docs.renovatebot.com/merge-confidence/) |

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### Release Notes

<details>
<summary>googleapis/python-bigquery</summary>

### [`v2.23.3`](https://togithub.com/googleapis/python-bigquery/blob/master/CHANGELOG.md#​2233-httpswwwgithubcomgoogleapispython-bigquerycomparev2232v2233-2021-08-06)

[Compare Source](https://togithub.com/googleapis/python-bigquery/compare/v2.23.2...v2.23.3)

</details>

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samples/geography/requirements.txt

@@ -1,4 +1,4 @@
 geojson==2.5.0
-google-cloud-bigquery==2.23.2
+google-cloud-bigquery==2.23.3
 google-cloud-bigquery-storage==2.6.2
 Shapely==1.7.1

samples/snippets/requirements.txt

@@ -1,4 +1,4 @@
-google-cloud-bigquery==2.23.2
+google-cloud-bigquery==2.23.3
 google-cloud-bigquery-storage==2.6.2
 google-auth-oauthlib==0.4.5
 grpcio==1.39.0