style(test): fix import ordering in dav backend tests

Signed-off-by: Jaggob <37583151+Jaggob@users.noreply.github.com>

Author: Jaggob

tests/unit/DAV/DeckCalendarBackendTest.php

@@ -7,8 +7,8 @@
 
 namespace OCA\Deck\DAV;
 
-use OCA\Deck\Db\BoardMapper;
 use OCA\Deck\Db\Board;
+use OCA\Deck\Db\BoardMapper;
 use OCA\Deck\Db\Card;
 use OCA\Deck\Db\Label;
 use OCA\Deck\Db\Stack;