Fixed TensorFlow version to 2.5.0

container/singularity/cc_py37.def

@@ -105,7 +105,7 @@ faiss.Kmeans(10, 20).train(numpy.random.rand(1000, 10).astype(numpy.float32))"'
     pip install scikit-learn                      # entry level ML in python
     pip install gensim                            # topic modelling word2vec
     if ! test_faiss; then printf -- "\033[31m ERROR: faiss is failing! \033[0m\n"; else printf -- '\033[32m SUCCESS: faiss is working correctly. \033[0m\n'; fi
-    pip install tensorflow                        # neural network library
+    pip install tensorflow==2.5.0                        # neural network library, fixed version because of AdaNet
     if ! test_faiss; then printf -- "\033[31m ERROR: faiss is failing! \033[0m\n"; else printf -- '\033[32m SUCCESS: faiss is working correctly. \033[0m\n'; fi
     pip install tensorflow-hub                    # repository of trained machine learning models
     pip install adanet                            # automl for NN