Installation request for yvoronoy/magento2-bash-completion dev-master -> satisfiable by yvoronoy/magento2-bash-completion[dev-master].
yvoronoy/magento2-bash-completion dev-master requires squizlabs/php_codesniffer ^2.6 -> satisfiable by squizlabs/php_codesniffer[2.6.0, 2.6.1, 2.6.2, 2.7.0, 2.7.1, 2.x-dev] but these conflict with your requirements or minimum-stability.
Problem 1