managedonly setting does not work correctly

[tstraley]

When the managedonly configuration setting is enabled, this tool ends up skipping those secrets that are properly managed by imagepullsecret-patcher, and does actually overwrite secrets that are not managed by it.

It appears to be a simple bug in the evaluation here: https://github.com/titansoft-pte-ltd/imagepullsecret-patcher/blob/master/main.go#L156

This should actually be

		if configManagedOnly && !isManagedSecret(secret) {
			return fmt.Errorf("[%s] Secret is present but unmanaged", namespace)
		}

[tstraley]

This project does not appear to be actively maintained, so I'm just going to leave this issue here for others to be aware. If PRs start getting acknowledged again in the future here, I can submit a PR to fix this.