chore(dependencies): update dependency pytest-cov to v4

Author: renovate[bot]

poetry.lock

@@ -17,7 +17,7 @@ python = "^3.7"
 [tool.poetry.dev-dependencies]
 black = "^21.12b0"
 pytest = "^7.1.2"
-pytest-cov = "^3.0.0"
+pytest-cov = "^4.0.0"
 pillow = "^7.2.0"
 codecov = "^2.1.12"
 pytest-benchmark = "^3.4.1"