Bump langchain-core from 0.3.34 to 0.3.43

Bumps [langchain-core](https://github.com/langchain-ai/langchain) from 0.3.34 to 0.3.43.
- [Release notes](https://github.com/langchain-ai/langchain/releases)
- [Commits](langchain-ai/langchain@langchain-core==0.3.34...langchain-core==0.3.43)

---
updated-dependencies:
- dependency-name: langchain-core
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements.txt

@@ -22,7 +22,7 @@ jsonpatch==1.33
 jsonpointer==3.0.0
 langchain==0.3.8
 langchain-community==0.3.8
-langchain-core==0.3.34
+langchain-core==0.3.43
 langchain-openai==0.2.9
 langchain-text-splitters==0.3.5
 langsmith==0.3.1