Bump langchain from 0.3.19 to 0.3.20 (#171)

Bumps [langchain](https://github.com/langchain-ai/langchain) from 0.3.19 to 0.3.20.
- [Release notes](https://github.com/langchain-ai/langchain/releases)
- [Commits](langchain-ai/langchain@langchain==0.3.19...langchain==0.3.20)

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

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

AI-Travel-Agent/requirements.txt

@@ -1,7 +1,7 @@
 amadeus==11.0.0
 ipykernel==6.29.5
 jupyter==1.1.1
-langchain==0.3.19
+langchain==0.3.20
 langchain-community==0.3.18
 streamlit==1.42.2
 huggingface_hub==0.29.1

Text-Summarizer-Browser-Plugin/requirements.txt

@@ -1,6 +1,6 @@
 flask==3.1.0
 flask_cors==5.0.1
-langchain==0.3.19
+langchain==0.3.20
 langchain-community==0.3.18
 sentence-transformers==3.4.1
 langchain_chroma==0.2.2