Support for PHP 8.0

Updated readme for V4

Added php 8.0 support

Worker and upgraded dragonmantank/cron-expression to v3

v3.1

Updated coverall badges

Scheduler v3

Dropped support for php < 7.1

Run job every X minutes

Ref #82

Run jobs at a specific date

Run jobs at specific date (#70)

* Run jobs on a specific date

* Documented all of the interval helpers

* StyleCI fixes

Hotfix mail transport when not specified

Merge pull request #45 from peppeocchi/hotfix-mail-transport-config

Fixed mail transport when not specified in scheduler constructor

Hotfix issue with invalid job path

Hotfix invalid job path (#36)

* Fix #35

Throw exception if when scheduling a php job the path doesn't exist

* StyleCI fix

* StyleCI fix

Added "before" method

This method is executed right before the job runs.

Jobs and scheduler custom run times

The scheduler can now run multiple times and the actual run time can now be faked.

Annotations and minor code fixes

v2.1.1

Added suggested change from @badyto