Makefile: update 'serve' target to use gunicorn exe
Makefile: update 'serve' target to use gunicorn exe

olaurendeau/v6_ui,olaurendeau/v6_ui,c2corg/v6_ui,Courgetteandratatouille/v6_ui,c2corg/v6_ui,Courgetteandratatouille/v6_ui,Courgetteandratatouille/v6_ui,olaurendeau/v6_ui,c2corg/v6_ui,Courgetteandratatouille/v6_ui,olaurendeau/v6_ui,c2corg/v6_ui