Bump langchain-core in /ai/gen-ai-agents/code-quality-agent/files

Bumps [langchain-core](https://github.com/langchain-ai/langchain) from 1.2.6 to 1.2.28.
- [Release notes](https://github.com/langchain-ai/langchain/releases)
- [Commits](langchain-ai/langchain@langchain-core==1.2.6...langchain-core==1.2.28)

---
updated-dependencies:
- dependency-name: langchain-core
  dependency-version: 1.2.28
  dependency-type: direct:production
...

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

Author: dependabot[bot]

ai/gen-ai-agents/code-quality-agent/files/requirements.txt

@@ -19,7 +19,7 @@ jiter==0.12.0
 jsonpatch==1.33
 jsonpointer==3.0.0
 langchain==1.2.3
-langchain-core==1.2.6
+langchain-core==1.2.28
 langchain-oci==0.2.1
 langchain-openai==1.1.7
 langgraph==1.0.5