Fix wrong namespace of RedirectRouteTest

[optior]

Q	A
Bug fix?	yes
New feature?	no
BC breaks?	no
Deprecations?	no
License	MIT

What's in this PR?

This PR fixes wrong namespace of RedirectRouteTest.

Why?

When running dump-autoload --classmap-authoritative there's a warning:

Generating optimized autoload files (authoritative)
Class Sulu\Bundle\RedirectBundle\Tests\Unit\Import\Converter\RedirectRouteTest located in ./vendor/sulu/redirect-bundle/Tests/Unit/Entity/RedirectRouteTest.php does not comply with psr-4 autoloading standard. Skipping.
composer/package-versions-deprecated: Generating version class...
composer/package-versions-deprecated: ...done generating version class
Generated optimized autoload files (authoritative) containing 8401 classes

[alexander-schranz]

Thank you for fixing this. Seems like we also did forget the .gitattributes file in this project, do you want to create that also: https://github.com/sulu/SuluArticleBundle/blob/2.x/.gitattributes

[alexander-schranz]

@optior Thank you!