fix date format Cron#62 (Cron#83)

Upgrade phpunit (Cron#75)

add php 7.4 to travis (Cron#61)

Fix to handle use of deprecated ContainerAwareCommand

Support for multiple doctrine manager

Signed-off-by: Gerd Christian Kunze <gerdchristian.kunze@googlemail.com>

makes cron.validator public

Always relead db

New long length for command field

Drop support for symfony <3.4

Revert "Revert "Explicitly register commands (Symfony 4 compat)""

This reverts commit 036b93d.