Drop Python 3.5 Windows wheels

It's EOL and AppVeyor builds are broken under it if we want to support Python 3.9.

Not fully deprecating 3.5 for now because it's still used on Toolforge.

appveyor.yml

@@ -24,14 +24,6 @@ environment:
       secure: gOIcvPxSC2ujuhwOzwj3v8xjq3CCYd8keFWVnguLM+gcL0e02qshDHy7gwZZwj0+
 
   matrix:
-    - PYTHON:         "C:\\Python35"
-      PYTHON_VERSION: "3.5"
-      PYTHON_ARCH:    "32"
-
-    - PYTHON:         "C:\\Python35-x64"
-      PYTHON_VERSION: "3.5"
-      PYTHON_ARCH:    "64"
-
     - PYTHON:         "C:\\Python36"
       PYTHON_VERSION: "3.6"
       PYTHON_ARCH:    "32"