Drop Python 2.7 testing on Windows again

Doing things the lazy way.

Author: takluyver

appveyor.yml

@@ -4,7 +4,6 @@ skip_branch_with_pr: true
 # environment variables
 environment:
   matrix:
-    - PYTHON: "C:\\Python27-x64"
     - PYTHON: "C:\\Python35-x64"
     - PYTHON: "C:\\Python36-x64"
     - PYTHON: "C:\\Python37-x64"