AppVeyor: Diversify VS & Py Versions

.appveyor.yml

@@ -1,30 +1,30 @@
 environment:
   matrix:
     - TARGET_ARCH: x86
-      CONDA_PY: 35
-      CONDA_INSTALL_LOCN: C:\\Miniconda35
+      CONDA_PY: 36
+      CONDA_INSTALL_LOCN: C:\\Miniconda36
       APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
       platform: x86
       SHARED: ON
 
     - TARGET_ARCH: x64
-      CONDA_PY: 35
-      CONDA_INSTALL_LOCN: C:\\Miniconda35-x64
+      CONDA_PY: 37
+      CONDA_INSTALL_LOCN: C:\\Miniconda37-x64
       APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
       platform: x64
       SHARED: ON
 
     - TARGET_ARCH: x86
-      CONDA_PY: 37
-      CONDA_INSTALL_LOCN: C:\\Miniconda37
-      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      CONDA_PY: 38
+      CONDA_INSTALL_LOCN: C:\\Miniconda
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
       platform: x86
       SHARED: ON
 
     - TARGET_ARCH: x64
-      CONDA_PY: 37
-      CONDA_INSTALL_LOCN: C:\\Miniconda37-x64
-      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      CONDA_PY: 39
+      CONDA_INSTALL_LOCN: C:\\Miniconda-x64
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
       platform: x64
       SHARED: OFF
 
@@ -115,6 +115,7 @@ before_build:
 
   # Compiler & Generator Selection
   - cmd: if "%APPVEYOR_BUILD_WORKER_IMAGE%"=="Visual Studio 2017" set OPENPMD_CMAKE_GENERATOR=Visual Studio 15 2017
+  - cmd: if "%APPVEYOR_BUILD_WORKER_IMAGE%"=="Visual Studio 2019" set OPENPMD_CMAKE_GENERATOR=Visual Studio 16 2019
   - cmd: if "%TARGET_ARCH%"=="x64" set OPENPMD_CMAKE_GENERATOR=%OPENPMD_CMAKE_GENERATOR% Win64
 #  - cmd: if "%TARGET_ARCH%"=="x86" "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" amd64_x86
   - cmd: if "%TARGET_ARCH%"=="x86" "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" x86