fix makefile

Author: beetleman

Makefile

@@ -2,11 +2,13 @@ tag = clojure-web-benchmark
 volumes = $(shell pwd)/artifacts:/app/artifacts
 run = docker run -v $(volumes) -it $(tag)
 
+dirs:
+	mkdir -p artifacts/plots
 docker-img:
 	docker build -t $(tag) .
-artifacts/results.csv: docker-img
+artifacts/results.csv: docker-img dirs
 	$(run) ./bench_all.sh
-plots: artifacts/results.csv docker-img
+plots: artifacts/results.csv docker-img dirs
 	$(run) python3 generate_plots.py
 clean:
 	$(run) rm -rf artifacts/*