Your requirements could not be resolved to an installable set of packages.
Problem 1
- Root composer.json requires oxid-solution-catalysts/paypal-module dev-master -> satisfiable by oxid-solution-catalysts/paypal-module[dev-master].
- oxid-solution-catalysts/paypal-module dev-master requires oxid-solution-catalysts/paypal-client v1.0.8 -> found oxid-solution-catalysts/paypal-client[v1.0.3] but it does not match the constraint.