deps: update dependency com.google.cloud:google-cloud-bigquery to v2.…

…1.8 (#926)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [com.google.cloud:google-cloud-bigquery](https://github.com/googleapis/java-bigquery) | `2.1.7` -> `2.1.8` | [![age](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-bigquery/2.1.8/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-bigquery/2.1.8/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-bigquery/2.1.8/compatibility-slim/2.1.7)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-bigquery/2.1.8/confidence-slim/2.1.7)](https://docs.renovatebot.com/merge-confidence/) |

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### Release Notes

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

### [`v2.1.8`](https://github.com/googleapis/java-bigquery/blob/master/CHANGELOG.md#&#8203;218-httpswwwgithubcomgoogleapisjava-bigquerycomparev217v218-2021-09-16)

[Compare Source](https://github.com/googleapis/java-bigquery/compare/v2.1.7...v2.1.8)

</details>

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samples/install-without-bom/pom.xml

@@ -47,7 +47,7 @@
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>google-cloud-bigquery</artifactId>
-      <version>2.1.7</version>
+      <version>2.1.8</version>
       <scope>test</scope>
     </dependency>
     <dependency>

samples/snapshot/pom.xml

@@ -46,7 +46,7 @@
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>google-cloud-bigquery</artifactId>
-      <version>2.1.7</version>
+      <version>2.1.8</version>
       <scope>test</scope>
     </dependency>
     <dependency>