Validate in registry logout as well

Author: pkwarren

private/buf/cmd/buf/command/registry/registrylogout/registrylogout.go

@@ -21,6 +21,7 @@ import (
 	"github.com/bufbuild/buf/private/bufpkg/bufconnect"
 	"github.com/bufbuild/buf/private/pkg/app/appcmd"
 	"github.com/bufbuild/buf/private/pkg/app/appext"
+	"github.com/bufbuild/buf/private/pkg/netext"
 	"github.com/bufbuild/buf/private/pkg/netrc"
 	"github.com/spf13/pflag"
 )
@@ -63,6 +64,9 @@ func run(
 	remote := bufconnect.DefaultRemote
 	if container.NumArgs() == 1 {
 		remote = container.Arg(0)
+		if _, err := netext.ValidateHostname(remote); err != nil {
+			return err
+		}
 	}
 	modified1, err := netrc.DeleteMachineForName(container, remote)
 	if err != nil {