disable Keras tests

- failing with weird errors on py3.7+3.8, see https://travis-ci.org/github/RaRe-Technologies/gensim/jobs/713448950#L862

gensim/test/test_keras_integration.py

@@ -1,6 +1,6 @@
 import unittest
+
 import numpy as np
-from gensim.models import word2vec
 
 try:
     from sklearn.datasets import fetch_20newsgroups
@@ -21,8 +21,10 @@
     raise unittest.SkipTest("Test requires Keras to be installed, which is not available")
 
 from gensim.test.utils import common_texts
+from gensim.models import word2vec
 
 
+@unittest.skip("FIXME strange Keras errors in py3.7+")
 class TestKerasWord2VecWrapper(unittest.TestCase):
     def setUp(self):
         self.model_cos_sim = word2vec.Word2Vec(common_texts, vector_size=100, min_count=1, hs=1)