Update Dockerfile

Dockerfile

@@ -15,7 +15,7 @@ RUN python -m pip install --no-cache-dir -r requirements.txt
 COPY . /app
 
 RUN mkdir -p /app/sessions && chmod 777 /app/sessions
-RUN mkdir -p /app/cache && chmod 777 /app/cache
+RUN mkdir -p /app/cache && chmod -R 777 /app/cache
 RUN alembic upgrade head
 
 # During debugging, this entry point will be overridden. For more information, please refer to https://aka.ms/vscode-docker-python-debug