Fix pytest version conflict (#18)

* Pin pytest version

* Pin pytest version

* Pin pytest version

* Pin pytest version

Author: bogdandm

.travis.yml

@@ -6,7 +6,9 @@ cache: pip
 install:
   - python setup.py sdist
   - python setup.py install
-  - pip install pytest>=4.4.0 pytest-cov requests coveralls codacy-coverage
+  - pip install pytest pytest-cov pytest-xdist requests coveralls codacy-coverage
+  - pip install --ignore-installed pytest>=4.4.0
+  - pytest --version
 
 script:
   - python setup.py test -a '--cov-config .coveragerc --cov=json_to_models -m "not no_expected" test/'

setup.py

@@ -45,6 +45,6 @@ def run_tests(self):
     },
     install_requires=required,
     cmdclass={"test": PyTest},
-    tests_require=["pytest", "pytest-xdist", "requests", "attrs"],
+    tests_require=["pytest>=4.4.0", "pytest-xdist", "requests", "attrs"],
     data_files=[('', ['pytest.ini', '.coveragerc', 'LICENSE'])]
 )