Support for predis 3.x

[gioialorusso]

Hi,
I see that the latest version of this package requires predis ^1.1
In my system I use predis for other purposes. I currently have it at version 1.1.1 but I want to upgrade to v3.0.1. If I try to increase the version of predis there is a version conflict:

Problem 1
- Root composer.json requires predis/predis =v3.0.1, found predis/predis[v3.0.1] but these were not loaded, likely because it conflicts with another require.
Problem 2
- code-orange/redis-counting-semaphore is locked to version v1.2 and an update of this package was not requested.
- code-orange/redis-counting-semaphore v1.2 requires predis/predis ^1.1 -> found predis/predis[v1.1.0, ..., v1.1.10] but it conflicts with your root composer.json require (=v3.0.1).

I can see that there are no new version of this library, so do you have any plans to release a version which is compatible with the latest version of predis?

Thanks,

[timvdalen]

I'm not currently using it with predis 3 so I'm not sure what would be required. If you're willing to open a PR, I'd be happy to merge it and release a new version.