Use pytest>=3.0.2

The bug that lead to pin it (pytest-dev/pytest#1888) was fixed in 3.0.2

.travis.yml

@@ -12,7 +12,7 @@ env:
  - LC_ALL=C LC_CTYPE=C
 script:
  # avoid VersionConflict when newer version is required
- - pip install -U 'pytest>=2.8,<3'
+ - pip install -U 'pytest>=3.0.2'
 
  # Output the env, because the travis docs just can't be trusted
  - env

setup.py

@@ -181,7 +181,7 @@ setup_params = dict(
     tests_require=[
         'setuptools[ssl]',
         'pytest-flake8',
-        'pytest>=2.8,<3',
+        'pytest>=3.0.2',
     ] + (['mock'] if sys.version_info[:2] < (3, 3) else []),
     setup_requires=[
     ] + pytest_runner + wheel,

tox.ini

@@ -4,6 +4,6 @@ envlist = py26,py27,py33,py34,py35,pypy,pypy3
 [testenv]
 deps=
 	pytest-flake8
-	pytest>=2.8,<3
+	pytest>=3.0.2
 passenv=APPDATA USERPROFILE HOMEDRIVE HOMEPATH windir
 commands=python setup.py test --addopts='-rsx'