remove py 3.5 support

Author: letmaik

.github/workflows/ci.yml

@@ -10,13 +10,8 @@ jobs:
         # FIXME should be include:, but individual entries are not supported yet, so work-around
         config:
 
-        # Use 2016 image for 3.5 as 2019 does not have VC++ 14.0 compiler.
+        # Use 2016 image as 2019 does not have VC++ 14.0 compiler.
         # https://github.community/t5/GitHub-Actions/Microsoft-Visual-C-14-0-compiler-not-available-on-Windows-2019/m-p/32871 
-        - os-image: windows-2016
-          os-name: windows
-          python-version: '3.5'
-          python-arch: '64'
-          numpy-version: '1.9'
         - os-image: windows-2016
           os-name: windows
           python-version: '3.6'