[ci] run tests only on 2.3 version.
[ci] run tests only on 2.3 version.

robfrawley/LiipImagineBundle,liip/LiipImagineBundle,liip/LiipImagineBundle,robfrawley/LiipImagineBundle,prolixtechnikos/LiipImagineBundle,prolixtechnikos/LiipImagineBundle,prolixtechnikos/LiipImagineBundle