fix install requirements for versions > 3.7

setup.py

@@ -1,12 +1,17 @@
 from distutils.core import setup
 from setuptools import find_packages
+import sys
+
+assert(sys.version_info >= (3, 0))
 
 exec(open('fishbook/version.py').read())
 
+requires = ['datajoint', 'nixio', 'numpy', 'PyYAML', 'scipy', 'backports-datetime-fromisoformat']
+
 setup(name='fishbook',
       version=__version__,
       packages=find_packages(exclude=['contrib', 'doc', 'tests*']),
       description='Database providing an overview of the electrophysiological data recorded in the group.',
       author='Jan Grewe',
-      requires=['datajoint', 'nixio', 'numpy', 'PyYAML', 'backports-datetime-fromisoformat']
+      install_requires=requires if sys.version_info < (3,7) else requires[:-1] 
       )