deps: update dependency com.google.cloud:google-cloud-pubsub-bom to v1.123.16 (#6070)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [com.google.cloud:google-cloud-pubsub-bom](https://togithub.com/googleapis/java-pubsub) | `1.123.15` -> `1.123.16` | [![age](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-pubsub-bom/1.123.16/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-pubsub-bom/1.123.16/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-pubsub-bom/1.123.16/compatibility-slim/1.123.15)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-pubsub-bom/1.123.16/confidence-slim/1.123.15)](https://docs.renovatebot.com/merge-confidence/) |

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### ⚠ Dependency Lookup Warnings ⚠

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### Release Notes

<details>
<summary>googleapis/java-pubsub (com.google.cloud:google-cloud-pubsub-bom)</summary>

### [`v1.123.16`](https://togithub.com/googleapis/java-pubsub/blob/HEAD/CHANGELOG.md#&#8203;112316-httpsgithubcomgoogleapisjava-pubsubcomparev112315v112316-2023-06-26)

[Compare Source](https://togithub.com/googleapis/java-pubsub/compare/v1.123.15...v1.123.16)

##### Dependencies

-   Update dependency com.google.protobuf:protobuf-java-util to v3.23.3 ([#&#8203;1634](https://togithub.com/googleapis/java-pubsub/issues/1634)) ([2481c4b](https://togithub.com/googleapis/java-pubsub/commit/2481c4b8799bbe78542b4a8dd6c2484be08f30a1))

</details>

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Author: renovate-bot

google-cloud-bom/pom.xml

@@ -224,7 +224,7 @@
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-pubsub-bom</artifactId>
-        <version>1.123.15</version>
+        <version>1.123.16</version>
         <type>pom</type>
         <scope>import</scope>
       </dependency>