A more future-proof tensorflow version dependency

.travis.yml

@@ -25,7 +25,7 @@ addons:
 install:
   - >
       conda create -q -n test-environment python=$TRAVIS_PYTHON_VERSION
-      numpy scipy nose pandas matplotlib mkl-service 'tensorflow>=2.2.0'
+      numpy scipy nose pandas matplotlib mkl-service 'tensorflow>=2.2.0,<2.3.0'
       pypandoc sphinx numpydoc
   - source activate test-environment
   - pip install nose-timer

requirements.txt

 six
 pandas>=0.20.3
-tensorflow>=2.2.0
+tensorflow>=2.2.0,<2.3.0
 appdirs
 scikit-learn
 mhcnames

setup.py

@@ -51,7 +51,7 @@ if __name__ == '__main__':
         'six',
         'pandas>=0.20.3',
         'appdirs',
-        'tensorflow>=2.2.0',
+        'tensorflow>=2.2.0,<2.3.0',
         'scikit-learn',
         'mhcnames',
         'pyyaml',