Since we are not using this as a direct dependency so better to remove it from the constraint otherwise it causes extra warning message to the stdout.
dep ensure -v
Warning: the following project(s) have [[constraint]] stanzas in Gopkg.toml:
✗ github.com/hooklift/iso9660
However, these projects are not direct dependencies of the current project:
they are not imported in any .go files, nor are they in the 'required' list in
Gopkg.toml. Dep only applies [[constraint]] rules to direct dependencies, so
these rules will have no effect.
Either import/require packages from these projects so that they become direct
dependencies, or convert each [[constraint]] to an [[override]] to enforce rules
on these projects, if they happen to be transitive dependencies.
Since we are not using this as a direct dependency so better to remove it from the constraint otherwise it causes extra warning message to the stdout.