Updated appveyor cfg and scripts

Author: Panos

.appveyor.yml

@@ -3,6 +3,7 @@ build:
   parallel: true
   verbosity: minimal
 skip_branch_with_pr: true
+image: Visual Studio 2019
 
 environment:
   global:
@@ -18,7 +19,6 @@ environment:
     # Python versions to build wheels for
     PYTHONVERS: C:\Python36-x64 C:\Python37-x64 C:\Python38-x64 C:\Python39-x64
     PYTHON_ARCH: "64"
-    MSVC: "Visual Studio 14 Win64"
 
 install:
   # If there is a newer build queued for the same PR, cancel this one.

ci/appveyor/build_ssh.bat

@@ -3,9 +3,7 @@ IF "%PYTHON_VERSION%" == "2.7" (exit 0)
 mkdir src
 cd src
 
-set CMAKE_PLATFORM="%MSVC%"
-
-cmake ..\libssh  -G %CMAKE_PLATFORM%               ^
+cmake ..\libssh                                    ^
       -DCMAKE_BUILD_TYPE=Release                   ^
       -DZLIB_LIBRARY=C:/zlib/lib/zlibstatic.lib    ^
       -DZLIB_INCLUDE_DIR=C:/zlib/include           ^

ci/appveyor/build_zlib.bat

@@ -2,19 +2,10 @@ IF "%PYTHON_VERSION%" == "2.7" (exit 0)
 
 mkdir zlib_build && cd zlib_build
 
-IF "%MSVC%" == "Visual Studio 9" (
-   ECHO "Building without platform set"
-   cmake ..\zlib-1.2.11 -G "NMake Makefiles"        ^
-       -DCMAKE_INSTALL_PREFIX="C:\zlib"             ^
-       -DCMAKE_BUILD_TYPE=Release                   ^
-       -DBUILD_SHARED_LIBS=OFF
-) ELSE (
-   ECHO "Building with platform %MSVC%"
-   cmake ..\zlib-1.2.11                             ^
-       -G"%MSVC%"                                   ^
-       -DCMAKE_INSTALL_PREFIX="C:\zlib"             ^
-       -DCMAKE_BUILD_TYPE=Release                   ^
-       -DBUILD_SHARED_LIBS=OFF
+cmake ..\zlib-1.2.11                             ^
+    -DCMAKE_INSTALL_PREFIX="C:\zlib"             ^
+    -DCMAKE_BUILD_TYPE=Release                   ^
+    -DBUILD_SHARED_LIBS=OFF
 )
 
 cmake --build . --config Release --target install