workflows: be more conservative about launching msys
workflows: be more conservative about launching msys

we don't want to lanuch it if we're only modifying a different workflow
template.

jpakkane/meson,jpakkane/meson,QuLogic/meson,mesonbuild/meson,jpakkane/meson,pexip/meson,pexip/meson,QuLogic/meson,QuLogic/meson,jpakkane/meson,jpakkane/meson,pexip/meson,mesonbuild/meson,pexip/meson,QuLogic/meson,pexip/meson,pexip/meson,QuLogic/meson,QuLogic/meson,mesonbuild/meson,jpakkane/meson,QuLogic/meson,pexip/meson,jpakkane/meson,jpakkane/meson,QuLogic/meson,mesonbuild/meson,pexip/meson,pexip/meson,mesonbuild/meson,jpakkane/meson,QuLogic/meson,pexip/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson