Bump dependencies (#195)

* Bump TF to 1.15.2

* Bump Gensim to 3.8.1

* Remove scipy from dependency list

* Bump numpy to 1.18.2

* Bump NLTK to 3.4.5

setup.py

@@ -67,14 +67,13 @@
     # requirements files see:
     # https://packaging.python.org/en/latest/requirements.html
     install_requires=[
-        'nltk~=3.4',
-        'numpy~=1.17',
-        'scipy~=1.3.1',
-        'gensim~=3.8.0',
-        'scikit-learn~=0.21.3',
+        'nltk~=3.4.5',
+        'numpy~=1.18.2',
+        'gensim~=3.8.1',
+        'scikit-learn~=0.22.2',
         'keras~=2.2.5',
         'h5py~=2.9',
-        'tensorflow~=1.14.0'
+        'tensorflow~=1.15.2'
     ],
 
     # List additional groups of dependencies here (e.g. development