Your requirements could not be resolved to an installable set of packages.
Problem 1
- Root composer.json requires oxid-esales/oxideshop-ce dev-b-7.0.x -> satisfiable by oxid-esales/oxideshop-ce[dev-b-7.0.x].
- oxid-esales/oxideshop-ce dev-b-7.0.x requires oxid-esales/oxideshop-composer-plugin dev-b-7.0.x -> found oxid-esales/oxideshop-composer-plugin[dev-b-7.0.x] but it does not match your minimum-stability.