keep just one clean version (starting from version v2.5.0)

[sensorario]

We have more version alive. I suggest to move everything to a new v2.5.0 and keep mantained just this instead of:

• 2.2
• 2.3
• 2.4

main issue here is that earlier versions use php 7.1 or 7.2 features. But this library works also with php 7.0 or older version. Because of it is hard and wasteful to spend time to keep versions maintained together, just one version could be a good solution.

[AlessandroMinoccheri]

It could be a good idea, we have to look at dependencies very well