deps: update dependency com.google.cloud:google-cloud-trace-bom to v1.2.1 (#898)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [com.google.cloud:google-cloud-trace-bom](https://github.com/googleapis/java-trace) | patch | `1.2.0` -> `1.2.1` |

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### Release Notes

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

### [`v1.2.1`](https://github.com/googleapis/java-trace/blob/master/CHANGELOG.md#&#8203;121-httpswwwgithubcomgoogleapisjava-tracecomparev120v121-2020-09-21)

[Compare Source](https://github.com/googleapis/java-trace/compare/v1.2.0...v1.2.1)

</details>

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Author: renovate-bot

pom.xml

@@ -564,7 +564,7 @@
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-trace-bom</artifactId>
-        <version>1.2.0</version>
+        <version>1.2.1</version>
         <type>pom</type>
         <scope>import</scope>
       </dependency>