Your requirements could not be resolved to an installable set of packages.
Problem 1
- Root composer.json requires phpbb/epv dev-master -> satisfiable by phpbb/epv[dev-master].
- phpbb/epv dev-master requires nikic/php-parser ^4.0 -> found nikic/php-parser[v4.0.0, ..., v4.19.4] but the package is fixed to v5.6.1 (lock file version) by a partial update and that version does not match. Make sure you list it as an argument for the update command.
Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.