conda: Use Tensorflow 1.15 from pip

Author: jonnor

environment.yml

@@ -8,10 +8,10 @@ dependencies:
   - scipy>=1.3.0
   - seaborn>=0.9.0
   - scikit-learn>=0.21.1
-  - tensorflow>=1.12
-  - keras>=2.2.4
   - jupyterlab>=1.1.4
   - pip:
     - soundfile>=0.10
     - librosa>=0.7.*
     - pytest>=5.1.3
+    - tensorflow==1.15
+    - keras==2.2.4