ci: run 2017/2019 on appveyor

gh-actions uses 2022

appveyor.yml

@@ -3,14 +3,9 @@ version: "{build}"
 environment:
   matrix:
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
-      generator: Visual Studio 15 2017
-      systemver: 10.0.18362.0
+      MSVC_VERSION: 2017
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
-      generator: Visual Studio 16 2019
-      systemver: 10.0.18362.0
-    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2022
-      generator: Visual Studio 17 2022
-      systemver: 10.0.22621.0
+      MSVC_VERSION: 2019
 
 configuration:
   - Release
@@ -20,12 +15,14 @@ clone_depth: 10
 clone_folder: c:\toml11
 
 install:
-- git submodule update --init --recursive
+  - git submodule update --init --recursive
 
 build_script:
+  - '"C:\Program Files (x86)\Microsoft Visual Studio\%MSVC_VERSION%\Community\VC\Auxiliary\Build\vcvarsall.bat" x64'
   - cd C:\toml11
-  - cmake -B build -G"%generator%" -DCMAKE_SYSTEM_VERSION="%systemver%" -A x64 -DCMAKE_CXX_STANDARD=11 -DTOML11_BUILD_TESTS=ON -DTOML11_PRECOMPILE=ON
-  - cmake --build build --config "%configuration%"
+  - cmake -B build -G"NMake Makefiles" -DCMAKE_BUILD_TYPE=%configuration% -DCMAKE_CXX_STANDARD=11 -DTOML11_BUILD_TESTS=ON -DBUILD_TESTING=ON -DTOML11_PRECOMPILE=ON
+  - cmake --build build
 
 test_script:
-  - ctest --test-dir build --build-config "%configuration%" --timeout 300 --output-on-failure
+  - cd build\tests\
+  - ctest --timeout 300 --output-on-failure