Remove Python 3.5 builds.

Also try using bionic with Python 3.6 instead of xenial
for the driving Python on travis-ci.

Author: charris

.appveyor.yml

@@ -27,14 +27,6 @@ environment:
       DAILY_COMMIT: master
 
   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

.travis.yml

@@ -18,23 +18,16 @@ env:
 
 language: python
 # Default Python version is usually 2.7
-python: 3.5
+python: 3.6
 sudo: required
-dist: trusty
+dist: bionic
 services: docker
 
 matrix:
   exclude:
-      # Exclude the default Python 3.5 build
-      - python: 3.5
+      # Exclude the default Python 3.6 build
+      - python: 3.6
   include:
-    - os: linux
-      env:
-        - MB_PYTHON_VERSION=3.5
-    - os: linux
-      env:
-        - MB_PYTHON_VERSION=3.5
-        - PLAT=i686
     - os: linux
       env:
         - MB_PYTHON_VERSION=3.6
@@ -56,12 +49,6 @@ matrix:
       env:
         - MB_PYTHON_VERSION=3.8
         - PLAT=i686
-    - os: osx
-      language: generic
-      osx_image: xcode6.4
-      env:
-        - MB_PYTHON_VERSION=3.5
-        - MB_PYTHON_OSX_VER=10.6
     - os: osx
       language: generic
       osx_image: xcode10.1