Switch to using pytest-cov for coverage

Author: Joel Collins

poetry.lock

@@ -18,7 +18,7 @@ zeroconf = ">=0.24.5,<0.26.0"
 [tool.poetry.dev-dependencies]
 pytest = "^5.2"
 black = {version = "^19.10b0",allow-prereleases = true}
-coverage = "^5.0.4"
+pytest-cov = "^2.8.1"
 numpy = "^1.18.2"
 
 [build-system]