Update versions of test dependencies (test_requirements.txt and test containers).

test_requirements.txt

@@ -1,25 +1,28 @@
-appdirs==1.4.3
-atomicwrites==1.3.0
-attrs==19.3.0
-black==19.3b0; python_version >= '3.6'
-click==7.0
-colorama==0.4.1
-coverage==4.5.4
+appdirs==1.4.4
+atomicwrites==1.4.0
+attrs==20.3.0
+black==19.10b0; python_version >= '3.6'
+click==7.1.2
+colorama==0.4.4
+coverage==5.3
 docopt==0.6.2
-flake8==3.7.9
+flake8==3.8.4
 flexmock==0.10.4
-isort==4.3.21
+isort==5.6.4
 mccabe==0.6.1
-more-itertools==7.2.0
-pluggy==0.13.0
-py==1.8.0
-pycodestyle==2.5.0
-pyflakes==2.1.1
+more-itertools==8.6.0
+pluggy==0.13.1
+pathspec==0.8.1
+py==1.9.0
+pycodestyle==2.6.0
+pyflakes==2.2.0
 pykwalify==1.7.0
-pytest==5.2.2
-pytest-cov==2.8.1
-python-dateutil==2.8.0
-PyYAML==5.1.2
-requests==2.22.0
+pytest==6.1.2
+pytest-cov==2.10.1
+python-dateutil==2.8.1
+PyYAML==5.3.1
+regex==2020.11.13
+requests==2.25.0
 ruamel.yaml>0.15.0,<0.17.0
-toml==0.10.0
+toml==0.10.2
+typed-ast==1.4.1