(windows installer) since we run this part in bash, OS is detected as msys

this is really ugly -- put up for debate later, just get it to work now

CURA-11622

profiles/cura.jinja

@@ -10,7 +10,7 @@ scripta*:compiler.cppstd=20
 umspatial*:compiler.cppstd=20
 dulcificum*:compiler.cppstd=20
 cura_settings*:compiler.cppstd=20
-{% if platform.system() == 'Windows' %}
+{% if platform.system() == 'msys' %}
 tools.env.virtualenv:powershell=True
 {% endif %}