Add int casting to getLastRestart method

[glioympas]

When cache driver is Redis and you retrieve a value from the store, it's automatically string type because of how Redis retrieves these values. Even if key "laravel-kafka:consumer:restart" is stored as an integer on RestartConsumersCommand, when retrieving, Redis will return that as a string.

The problem is the combination of strict_types=1 and type hinting. PHP can't automatically convert that to an integer, so there is a type error exception.

On this PR we cast the result of getLastRestart, so it's always an integer.

[mateusjunges]

Thank you @glioympas!

[panVag]

@mateusjunges can we please cut a new minor version for this one?

[duckarcher]

+1 for the above. thanks in advance @mateusjunges. i will use this new version as long as it's out.