too new? pin 3.7 python instead

Author: gonzalocasas

.travis.yml

@@ -12,14 +12,14 @@ matrix:
       env:
         - PATH=/c/Python27:/c/Python27/Scripts:$PATH
         - TRAVIS_PYTHON_VERSION=2.7
-    - name: "Python 3.8: Windows"
+    - name: "Python 3.7: Windows"
       os: windows
       language: shell
       before_install:
-        - choco install python3
+        - choco install python3 --version=3.7.4
       env:
-        - PATH=/c/Python38:/c/Python38/Scripts:$PATH
-        - TRAVIS_PYTHON_VERSION=3.8
+        - PATH=/c/Python37:/c/Python37/Scripts:$PATH
+        - TRAVIS_PYTHON_VERSION=3.7
     - name: "Python 3.7: Xenial Linux"
       python: 3.7
       dist: xenial