update : dev-requirements updated.

dev-requirements.txt

@@ -1,9 +1,11 @@
+art==5.2
 vulture>=1.0
 bandit>=1.5.1
 pydocstyle>=3.0.0
 setuptools>=40.8.0
 codecov>=2.0.15
+coverage>=4.1
 pytest>=4.3.1
 pytest-cov>=2.6.1
-art>=1.8
+matplotlib>=3.0.0