Deprecation notices on v3.13.0 and PHP 8.1.14

[crmpicco]

Following on from https://github.com/chargebee/chargebee-php/issues/40, I am experiencing a whole bunch of deprecation notices in my application originating from the chargebee/chargebee-php project.

User Deprecated: Method "Countable::count()" might add "int" as a native return type declaration in the future. Do the same in implementation "ChargeBee\ChargeBee\ListResult" now to avoid errors or add an explicit @return annotation to suppress this message. 

User Deprecated: Method "ArrayAccess::offsetSet()" might add "void" as a native return type declaration in the future. Do the same in implementation "ChargeBee\ChargeBee\ListResult" now to avoid errors or add an explicit @return annotation to suppress this message. 

User Deprecated: Method "ArrayAccess::offsetUnset()" might add "void" as a native return type declaration in the future. Do the same in implementation "ChargeBee\ChargeBee\ListResult" now to avoid errors or add an explicit @return annotation to suppress this message. 

I am on v3.13.0 and PHP 8.1.14.