test-windows.yml: Try switching to PowerShell as the shell, instead of cmd

Author: stephengtuggy

.github/workflows/test-windows.yml

@@ -64,16 +64,14 @@ jobs:
         faber --info=tools cxx
 
     - name: build
-      shell: cmd
+      shell: pwsh
       run: |
         faber --builddir=build cxx.name=msvc --log=commands --log=output --with-boost-include="${{ github.workspace }}/vcpkgInstalled/x64-windows/include" -j4
-        if %errorlevel% neq 0 exit %errorlevel%
 
     - name: test
-      shell: cmd
+      shell: pwsh
       run: |
         faber --builddir=build cxx.name=msvc --with-boost-include="${{ github.workspace }}/vcpkgInstalled/x64-windows/include" -j4 test.report
-        if %errorlevel% neq 0 exit %errorlevel%
 
     - name: Save vcpkg cache
       id: cache-vcpkg-save