Update appveyor.yml

appveyor.yml

@@ -1,8 +1,9 @@
+image:
+  - Visual Studio 2019
 environment:
     global:
-        PYTHON: "C:\\conda"
+        PYTHON: "C:\\Python38-x64\\python3.exe"
         MINICONDA_VERSION: "latest"
-        CMD_IN_ENV: "cmd /E:ON /V:ON /C .\\ci-helpers\\appveyor\\windows_sdk.cmd"
         PYTHON_ARCH: "64" # needs to be set for CMD_IN_ENV to succeed. If a mix
                           # of 32 bit and 64 bit builds are needed, move this
                           # to the matrix section.
@@ -15,14 +16,11 @@ matrix:
 
 platform:
     -x64
-
+    
 install:
-    - "git clone --depth 1 git://github.com/astropy/ci-helpers.git"
-    - "powershell ci-helpers/appveyor/install-miniconda.ps1"
-    - "SET PATH=%PYTHON%;%PYTHON%\\Scripts;%PATH%"
-    - "activate test"
-    - "%CMD_IN_ENV% pip install -r requirements.txt"
-    - "%CMD_IN_ENV% pip install git+https://github.com/dvolgyes/zenodo_get"
+    - "SET PATH=C:\\Python38-x64;%PATH%"
+    - "python -m pip install -r requirements.txt"
+    - "python -m pip install git+https://github.com/dvolgyes/zenodo_get"
     - choco install --accept-license wget
 
 build: off