[composer]: Update rector/rector requirement from ^0.15.21 || ^0.16.0 || ^0.17.0 || ^0.18.0 to ^0.15.21 || ^0.16.0 || ^0.17.0 || ^0.18.0 || ^0.19.0

[composer]: Update rector/rector requirement from ^0.15.21 || ^0.16.0 || ^0.17.0 || ^0.18.0 to ^0.15.21 || ^0.16.0 || ^0.17.0 || ^0.18.0 || ^0.19.0 #106