CakePHP ORM pulls incompatible dependencies

**Steps**
Install cakephp/orm 3.0 via composer on PHP 5.6.

**Expected**
All installed dependencies compatible with that orm version.

**Actual**
Installed dependency cakephp/event 3.10 throws a deprecation.

**Temporary workaround**
Manually set version of dependencies (cakephp/event, cakephp/validation) to 3.0.