Root composer.json requires muqsit/simple-packet-handler ^0.1.3 -> satisfiable by muqsit/simple-packet-handler[0.1.3].
muqsit/simple-packet-handler 0.1.3 requires pocketmine/pocketmine-mp ^4.0.0 -> found pocketmine/pocketmine-mp[4.0.0, ..., 4.26.0] but it conflicts with your root composer.json require (^5.15).
Problem 1