[BUGFIX] Set correct variable type in Extension model

In the Extension model from the extension manager the variable type of
$dependencies is wrong. This should be
\TYPO3\CMS\Extensionmanager\Domain\Model\Dependency
instead of Tx_Extensionmanager_Utility_Dependency.

Resolves: #73624
Releases: master, 7.6
Change-Id: Ibbdd9933ff6c312ad7759574be425b4e57eb1f04
Reviewed-on: https://review.typo3.org/46848


Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>
Reviewed-by: Stephan Großberndt <stephan@grossberndt.de>
Reviewed-by: Daniel Goerz <ervaude@gmail.com>
Tested-by: Daniel Goerz <ervaude@gmail.com>
Reviewed-by: Nicole Cordes <typo3@cordes.co>
Tested-by: Nicole Cordes <typo3@cordes.co>