Create initial check.yml github action.
Create initial check.yml github action.

Check in initial unmodified cmake action as generated using the github UI.
librsync/librsync,dbaarda/librsync,sourcefrog/librsync,librsync/librsync,dbaarda/librsync,librsync/librsync,dbaarda/librsync,dbaarda/librsync,sourcefrog/librsync,sourcefrog/librsync,librsync/librsync,sourcefrog/librsync