Test with python 3.7 as dependencies require it

Author: Eigenstate

.travis.yml

@@ -1,6 +1,7 @@
 language: python
+dist: xenial # Required for Python >= 3.7
 python:
-    - "3.6"
+    - "3.7"
 install:
     - wget https://repo.continuum.io/miniconda/Miniconda-latest-Linux-x86_64.sh -O miniconda.sh;
     - bash miniconda.sh -b -p $HOME/miniconda