Dockerfile: Add sftp server binary
Dockerfile: Add sftp server binary

ar-jan/restic,middelink/restic,stuertz/restic,middelink/restic,byo/restic,jayme-github/restic,arithmetric/restic,byo/restic,restic/restic,kurin/restic,mappu/restic,ckemper67/restic,fawick/restic,ar-jan/restic,stuertz/restic,jayme-github/restic,fawick/restic,bchapuis/restic,restic/restic,kurin/restic