chore(deps): bump chromadb from 0.5.4 to 0.5.5 in /backend

Bumps [chromadb](https://github.com/chroma-core/chroma) from 0.5.4 to 0.5.5.
- [Release notes](https://github.com/chroma-core/chroma/releases)
- [Changelog](https://github.com/chroma-core/chroma/blob/main/RELEASE_PROCESS.md)
- [Commits](https://github.com/chroma-core/chroma/compare/0.5.4...0.5.5

)

---
updated-dependencies:
- dependency-name: chromadb
  dependency-type: direct:production
  update-type: version-update:semver-patch
...
Signed-off-by: dependabot[bot] <support@github.com>

backend/requirements.txt

@@ -39,7 +39,7 @@ langchain-community==0.2.10
 langchain-chroma==0.1.2
 
 fake-useragent==1.5.1
-chromadb==0.5.4
+chromadb==0.5.5
 sentence-transformers==3.0.1
 pypdf==4.3.1
 docx2txt==0.8