Change embeded alert property attributes

[sungjin-woo]

I realized the properties of basic alert references inside RMUniversalAlert doesn't have memory management attributes.

As you know, the default property attributes with ARC is strong.

• https://useyourloaf.com/blog/default-property-attributes-with-arc/

@property NSArray *name;
@property (strong, atomic, readwrite) NSArray *name;

I think they don't need to be strong references.
It causes memory leak sometimes since iOS 11.

So, I add weak attribute on the properties.

@property (nonatomic, weak) UIAlertController *alertController;
@property (nonatomic, weak) UIAlertView *alertView;
@property (nonatomic, weak) UIActionSheet *actionSheet;

Could you check this out, please?