Fix Docker cache bug

Fixes issue #5

Dockerfile

@@ -1,7 +1,6 @@
 FROM python:3.9
 
 # Add settings taken from huggingface default container.
-WORKDIR /home/user/app
 RUN useradd -m -u 1000 user
 RUN apt-get update && apt-get install -y \
     git git-lfs ffmpeg 	libsm6 	libxext6 \
@@ -13,15 +12,17 @@ RUN apt-get update && apt-get install -y \
 RUN pip install 'setuptools<58'
 
 # Install drexel_metadata dependencies
-COPY requirements.txt requirements.txt
-RUN pip install -r requirements.txt
+COPY requirements.txt /tmp/requirements.txt
+RUN pip install -r /tmp/requirements.txt
 
 # Install gradio after main dependencies to prevent
 # `cannot import name 'deprecated' from 'typing_extensions'` error.
 RUN pip install gradio
 
+USER user
+WORKDIR /home/user/app
 # Cache matplotlib fonts to improve startup time.
-RUN python -c "import matplotlib.pyplot"
+RUN mkdir /home/user/.cache && python -c "import matplotlib.pyplot"
 
-COPY . /home/user/app
+COPY --chown=user . /home/user/app
 CMD python app.py