Remove the cfg argument from Step.Execute [#67]

This is the first step toward removing run.Config entirely. InitKube was
the only Step that even used cfg in its Execute function; the rest just
discarded it.

internal/run/uninstall.go

@@ -23,7 +23,7 @@ func NewUninstall(cfg env.Config) *Uninstall {
 }
 
 // Execute executes the `helm uninstall` command.
-func (u *Uninstall) Execute(_ Config) error {
+func (u *Uninstall) Execute() error {
 	return u.cmd.Run()
 }