feat: update requirement by adding unicorn

requirements.txt

@@ -3,7 +3,7 @@
 # Web framework
 fastapi>=0.111.0
 uvicorn[standard]>=0.29.0
-python-multipart>=0.0.9      # required for FastAPI file/form uploads
+python-multipart>=0.0.9
 
 # Environment
 python-dotenv>=1.0.0
@@ -20,4 +20,7 @@ pdfplumber>=0.11.0
 # Retrieval / ranking
 rank-bm25>=0.2.2
 scikit-learn>=1.4.0
-numpy>=1.26.0
+numpy>=1.26.0
+
+# Validation
+pydantic>=2.7.0