dev(hansbug): use newer test packages

requirements-test.txt

 coverage>=5
 mock>=4.0.3
 flake8~=3.5
-pytest~=5.4.3
-pytest-cov~=2.10.1
-pytest-mock~=3.5.1
-pytest-forked~=1.3.0
-pytest-xdist~=1.34.0
-pytest-timeout~=1.4.2
-pytest-rerunfailures~=9.1.1
+pytest~=6.2.5
+pytest-cov~=3.0.0
+pytest-mock~=3.6.1
+pytest-xdist>=1.34.0
+pytest-rerunfailures~=10.2
+pytest-timeout~=2.0.2
 pytest-benchmark~=3.4.0
 numpy>=1.19,<2
 torch>=1.3.1,<=1.8.0