Fix create dir that already exists

Author: bolasim

truss/templates/server.Dockerfile.jinja

@@ -53,7 +53,7 @@ COPY ./{{config.data_dir}} /app/data
 {%- endif %}
 
 {%- if config.hf_cache != None %}
-RUN mkdir /app
+RUN mkdir -p /app
 RUN curl -s https://baseten-public.s3.us-west-2.amazonaws.com/bin/b10cp-5fe8dc7da-linux-amd64 -o /app/b10cp; chmod +x /app/b10cp
 ENV B10CP_PATH_TRUSS /app/b10cp
 COPY ./cache_requirements.txt /app/cache_requirements.txt