deps: update dependency com.google.api.grpc:proto-google-cloud-aiplatform-v1beta1 to v0.15.3 (#928)

[![Mend Renovate](https://app.renovatebot.com/images/banner.svg)](https://renovatebot.com)

This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [com.google.api.grpc:proto-google-cloud-aiplatform-v1beta1](https://togithub.com/googleapis/java-) | `0.15.2` -> `0.15.3` | [![age](https://badges.renovateapi.com/packages/maven/com.google.api.grpc:proto-google-cloud-aiplatform-v1beta1/0.15.3/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/maven/com.google.api.grpc:proto-google-cloud-aiplatform-v1beta1/0.15.3/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/maven/com.google.api.grpc:proto-google-cloud-aiplatform-v1beta1/0.15.3/compatibility-slim/0.15.2)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/maven/com.google.api.grpc:proto-google-cloud-aiplatform-v1beta1/0.15.3/confidence-slim/0.15.2)](https://docs.renovatebot.com/merge-confidence/) |

---

### Configuration

📅 **Schedule**: At any time (no schedule defined).

🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

♻ **Rebasing**: Renovate will not automatically rebase this PR, because other commits have been found.

🔕 **Ignore**: Close this PR and you won't be reminded about this update again.

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, click this checkbox. ⚠ **Warning**: custom changes will be lost.

---

This PR has been generated by [Mend Renovate](https://www.mend.io/free-developer-tools/renovate/). View repository job log [here](https://app.renovatebot.com/dashboard#github/googleapis/java-aiplatform).

Author: renovate-bot

aiplatform/snippets/pom.xml

@@ -60,7 +60,7 @@
     <dependency>
       <groupId>com.google.api.grpc</groupId>
       <artifactId>proto-google-cloud-aiplatform-v1beta1</artifactId>
-      <version>0.15.2</version>
+      <version>0.15.3</version>
     </dependency>
 
   </dependencies>