Replace createCancellableContext with signal.NotifyContext

[jonjohnsonjr]

https://tip.golang.org/pkg/os/signal/#NotifyContext

https://github.com/google/ko/blob/bd91eab30cf04eb8d567930c32f87564f753a399/pkg/commands/config.go#L115-L126

Requires go 1.16

[github-actions]

This issue is stale because it has been open for 90 days with no
activity. It will automatically close after 30 more days of
inactivity. Reopen the issue with /reopen. Mark the issue as
fresh by adding the comment /remove-lifecycle stale.

[imjasonh]

/remove-lifecycle stale

[github-actions]

This issue is stale because it has been open for 90 days with no
activity. It will automatically close after 30 more days of
inactivity. Keep fresh with the 'lifecycle/frozen' label.

[jonjohnsonjr]

@imjasonh with the bump to 1.17 we can do this too