Fix HfFolder error - use sentence-transformers 2.3.1 which doesn't require HfFolder

sentence-transformers 2.2.2 requires HfFolder which was removed from newer huggingface-hub versions.
sentence-transformers 2.3.1 (Dec 2023) removed HfFolder dependency.

Updated versions:
- sentence-transformers: 2.2.2 -> 2.3.1
- transformers: 4.30.2 -> 4.36.0
- torch: 2.0.1 -> 2.1.0
- huggingface-hub: 0.10.1 -> 0.20.1

All versions from late 2023 era, tested compatible set.

requirements.txt

@@ -1,8 +1,8 @@
-# Core ML/NLP - using older compatible versions
-sentence-transformers==2.2.2
+# Core ML/NLP - using stable compatible versions
+sentence-transformers==2.3.1
 hnswlib==0.8.0
-transformers==4.30.2
-torch==2.0.1
+transformers==4.36.0
+torch==2.1.0
 numpy==1.24.3
 scikit-learn==1.5.0
 scipy==1.13.0
@@ -26,8 +26,8 @@ pandas==2.2.2
 rdflib==7.0.0
 SPARQLWrapper==2.0.0
 
-# Hugging Face - pin to version with HfFolder for sentence-transformers 2.2.2
-huggingface-hub==0.10.1
+# Hugging Face - compatible versions (sentence-transformers 2.3+ doesn't need HfFolder)
+huggingface-hub==0.20.1
 
 # Web interface
 streamlit==1.36.0