add python 3.9 to appveyor

also switch appveyor to visual studio 2019
also remove python 3.5 and jdk 9 and 10 tests
since they do not work on visual studio 2019 image

appveyor.yml

@@ -1,20 +1,10 @@
-image: Visual Studio 2017
+image: Visual Studio 2019
 
 environment:
 
   matrix:
-    - PYTHON: "C:\\Python35"
-      JAVA_HOME: "C:\\Program Files (x86)\\Java\\jdk1.8.0"
-
-    - PYTHON: "C:\\Python35-x64"
-      JAVA_HOME: "C:\\Program Files\\Java\\jdk1.8.0"
     - PYTHON: "C:\\Python36-x64"
       JAVA_HOME: "C:\\Program Files\\Java\\jdk1.8.0"
-
-    - PYTHON: "C:\\Python36-x64"
-      JAVA_HOME: "C:\\Program Files\\Java\\jdk9"
-    - PYTHON: "C:\\Python36-x64"
-      JAVA_HOME: "C:\\Program Files\\Java\\jdk10"
     - PYTHON: "C:\\Python36-x64"
       JAVA_HOME: "C:\\Program Files\\Java\\jdk11"
     - PYTHON: "C:\\Python37-x64"
@@ -23,6 +13,8 @@ environment:
       JAVA_HOME: "C:\\Program Files\\Java\\jdk12"
     - PYTHON: "C:\\Python38-x64"
       JAVA_HOME: "C:\\Program Files\\Java\\jdk11"
+    - PYTHON: "C:\\Python39-x64"
+      JAVA_HOME: "C:\\Program Files\\Java\\jdk11"
 
 build: off