Update pytest to v6.2.2

Author: natct10

dev-requirements.txt

@@ -10,7 +10,7 @@ seaborn==0.11.0
 loguru==0.5.3
 tensorflow==2.4.0
 ruamel.yaml==0.16.12
-pytest==6.2.0
+pytest==6.2.2
 pytest-cov==2.10.1
 flake8==3.8.3
 twine==3.2.0