repin test reqs

Author: mikejhuang

test_requirements.txt

@@ -1,8 +1,8 @@
-pytest
-pytest-cov
-pytest-cover
-pytest-pep8
-pytest-xdist
+pytest>=4.4.0
+pytest-cov>=2.6.1,<3.0.0
+pytest-cover>=3.0.0,<4.0.0
+pytest-pep8>=1.0.6,<2.0.0
+pytest-xdist>=1.14,<2.0.0
 pytest-mock>=1.5.0,<3.0.0
 mock>=1.0.1,<5.0.0
 coverage>=3.7.1,<6.0.0