Remove '-A' option for VS 2019 CI

Author: flexferrum

.github/workflows/windows-build.yml

@@ -46,7 +46,6 @@ jobs:
             run-machine: windows-2019
             generator: Visual Studio 16 2019
             vc_vars:  C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Auxiliary\Build\vcvars64.bat
-            extra_flags: -A Win64
 
 
     steps: