fix: examples/langchain-python-rag-privategpt/requirements.txt (#3382)

examples/langchain-python-rag-privategpt/requirements.txt

@@ -11,4 +11,5 @@ tabulate==0.9.0
 pandoc==2.3
 pypandoc==1.11
 tqdm==4.66.1
-sentence_transformers==2.2.2
+sentence_transformers==2.2.2
+numpy>=1.22.2 # not directly required, pinned by Snyk to avoid a vulnerability