"slices" module only in go 1.21

[DrDaveD]

I attempted to update apptainer to use a commit on the current main branch of containers/image/v5, but when compiling with go 1.20.10 it got this compilation error:

/go/pkg/mod/github.com/containers/image/[email protected]/pkg/blobinfocache/internal/prioritize/prioritize.go:6:2: package slices is not in GOROOT (/usr/local/go/src/slices)

#2340 said it was about updating to go 1.20, but it started using the "slices" package which is only in go 1.21 and later.

[mtrmac]

Oops, I missed that. #2343 should fix it.

Thanks for the report!