psr3: bump minimum Monolog version
psr3: bump minimum Monolog version

Raise minimum version to match the version in use on the WMF production
cluster.

Change-Id: Ib9de6d0b634b62f5dd40fb1850a377c5d994c422

stuartbman/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,stuartbman/mediawiki-vagrant,stuartbman/mediawiki-vagrant,wikimedia/mediawiki-vagrant,stuartbman/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,stuartbman/mediawiki-vagrant,stuartbman/mediawiki-vagrant,wikimedia/mediawiki-vagrant,stuartbman/mediawiki-vagrant