chore(deps): Bump com.openai:openai-java from 4.26.0 to 4.28.0

Bumps [com.openai:openai-java](https://github.com/openai/openai-java) from 4.26.0 to 4.28.0.
- [Release notes](https://github.com/openai/openai-java/releases)
- [Changelog](https://github.com/openai/openai-java/blob/main/CHANGELOG.md)
- [Commits](openai/openai-java@v4.26.0...v4.28.0)

---
updated-dependencies:
- dependency-name: com.openai:openai-java
  dependency-version: 4.28.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

parent/pom.xml

@@ -430,7 +430,7 @@
         <olingo4-version>5.0.0</olingo4-version>
         <ognl-version>3.4.10</ognl-version>
         <mcp-java-sdk-version>1.0.0</mcp-java-sdk-version>
-        <openai-java-version>4.26.0</openai-java-version>
+        <openai-java-version>4.28.0</openai-java-version>
         <openapi-generator-version>7.20.0</openapi-generator-version>
         <openjpa-version>4.1.1</openjpa-version>
         <opensearch-rest-client-version>3.5.0</opensearch-rest-client-version>