ci: Try not to call vcvarsall.bat (should be call by cxx-compiler activation script

Author: jorisv

.github/workflows/conda/environment_windows.yml

@@ -8,5 +8,6 @@ dependencies:
   - pkg-config
   - boost
   - ccache
+  - cxx-compiler
   - ninja
   - scipy

.github/workflows/windows-conda.yml

@@ -65,10 +65,6 @@ jobs:
       run: |
         call conda list
 
-        :: start building
-        call "%programfiles%\Microsoft Visual Studio\2022\Enterprise\VC\Auxiliary\Build\vcvarsall.bat" amd64
-        if errorlevel 1 exit 1
-
         mkdir build
         pushd build
         cmake ^