added sessions dir with relevant permissions to dockerfile

Author: BrunoV21

examples/hf_demo_space/Dockerfile

@@ -17,6 +17,7 @@ RUN mkdir -p /app/.files && chmod 777 /app/.files
 RUN mkdir -p /app/logs && chmod 777 /app/logs
 RUN mkdir -p /app/observability_data && chmod 777 /app/observability_data
 RUN mkdir -p /app/storage && chmod 777 /app/storage
+RUN mkdir -p /app/sessions && chmod 777 /app/sessions
 
 # Copy the current repository into the container
 COPY . /app