reduce image size

Added the option `--no-cache-dir` to the `pip3 install` commands on the Dockerfile to reduce the docker image resulting size to 1.89 GB from 2.27 GB.

Dockerfile

@@ -41,8 +41,8 @@ WORKDIR /app/backend
 
 COPY ./backend/requirements.txt ./requirements.txt
 
-RUN pip3 install torch torchvision torchaudio --index-url https://download.pytorch.org/whl/cpu
-RUN pip3 install -r requirements.txt
+RUN pip3 install torch torchvision torchaudio --index-url https://download.pytorch.org/whl/cpu --no-cache-dir
+RUN pip3 install -r requirements.txt --no-cache-dir
 
 # RUN python -c "from sentence_transformers import SentenceTransformer; model = SentenceTransformer('all-MiniLM-L6-v2')"