deps: update actions/github-script action to v6 (#791)

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This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [actions/github-script](https://togithub.com/actions/github-script) | action | major | `v5` -> `v6` |

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### Release Notes

<details>
<summary>actions/github-script</summary>

### [`v6`](https://togithub.com/actions/github-script/compare/v5...v6)

[Compare Source](https://togithub.com/actions/github-script/compare/v5...v6)

</details>

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README.md

@@ -38,7 +38,7 @@ If you are using Maven without BOM, add this to your dependencies:
 If you are using Gradle 5.x or later, add this to your dependencies
 
 ```Groovy
-implementation platform('com.google.cloud:libraries-bom:24.2.0')
+implementation platform('com.google.cloud:libraries-bom:24.3.0')
 
 implementation 'com.google.cloud:google-cloud-aiplatform'
 ```