Your requirements could not be resolved to an installable set of packages.
Problem 1
- Installation request for tuupola/slim-image-resize ^0.6.1 → satisfiable by tuupola/slim-image-resize[0.6.1].
- tuupola/slim-image-resize 0.6.1 requires slim/slim ~2.3 → satisfiable by slim/slim[2.3.0, 2.3.1, 2.3.2, 2.3.3, 2.3.4, 2.3.5, 2.4.0, 2.4.1, 2.4.2, 2.4.3, 2.5.0, 2.6.0, 2.6.1, 2.6.2, 2.x-dev] but these conflict with your requirements or minimum-stability.
Installation failed, reverting ./composer.json to its original content.