Dockerfile: install fuse-overlayfs from apk
Dockerfile: install fuse-overlayfs from apk

fuse-overlayfs is available as an apk since Alpine 3.14.

Signed-off-by: Akihiro Suda <10ddef0dea2a66ab193b07198faa879adcb213d8@hco.ntt.co.jp>

tonistiigi/buildkit_poc,tonistiigi/buildkit_poc