deps: update dependency com.google.cloud:google-cloud-bigquery to v2.15.0 (#4957)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [com.google.cloud:google-cloud-bigquery](https://togithub.com/googleapis/java-bigquery) | `2.14.7` -> `2.15.0` | [![age](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-bigquery/2.15.0/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-bigquery/2.15.0/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-bigquery/2.15.0/compatibility-slim/2.14.7)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-bigquery/2.15.0/confidence-slim/2.14.7)](https://docs.renovatebot.com/merge-confidence/) |

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### Release Notes

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

### [`v2.15.0`](https://togithub.com/googleapis/java-bigquery/blob/HEAD/CHANGELOG.md#&#8203;2150-httpsgithubcomgoogleapisjava-bigquerycomparev2147v2150-2022-08-25)

[Compare Source](https://togithub.com/googleapis/java-bigquery/compare/v2.14.7...v2.15.0)

##### Features

-   add preview support for default values ([#&#8203;2244](https://togithub.com/googleapis/java-bigquery/issues/2244)) ([fd3d3c5](https://togithub.com/googleapis/java-bigquery/commit/fd3d3c57afed84b4d00aab438d79472a6afa001b))

</details>

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Author: renovate-bot

google-cloud-bom/pom.xml

@@ -221,7 +221,7 @@
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-bigquery</artifactId>
-        <version>2.14.7</version>
+        <version>2.15.0</version>
       </dependency>
       <dependency>
         <groupId>com.google.cloud</groupId>