Add 'format' and 'lint' targets to the Makefile

Author: aecio

Makefile

@@ -1,6 +1,14 @@
-all: test
+SRC := ./bdikit/
 
-PHONY: test
+all: lint test
+
+PHONY: format test lint
+
+lint:
+	black --check ${SRC}
 
 test:
 	python3 -m pytest
+
+format:
+	black ${SRC}