[TASK] Remove unnecessary parentheses

The first patch https://review.typo3.org/#/c/55952/
missed two places because of a rebase issue.

Resolves: #84092
Releases: master
Change-Id: Ie646cdfdb4900a3a7b969b4745852f7c76139df5
Reviewed-on: https://review.typo3.org/55991
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>

typo3/sysext/workspaces/Classes/Service/StagesService.php

@@ -316,7 +316,7 @@ public function getNextStage($stageId)
         $workspaceStageRecs = $this->getStagesForWS();
         if (is_array($workspaceStageRecs) && !empty($workspaceStageRecs)) {
             reset($workspaceStageRecs);
-            while (!is_null($workspaceStageRecKey = key($workspaceStageRecs))) {
+            while ($workspaceStageRecKey = key($workspaceStageRecs) !== null) {
                 $workspaceStageRec = current($workspaceStageRecs);
                 if ($workspaceStageRec['uid'] == $stageId) {
                     $nextStage = next($workspaceStageRecs);
@@ -383,7 +383,7 @@ public function getPrevStage($stageId)
         $workspaceStageRecs = $this->getStagesForWS();
         if (is_array($workspaceStageRecs) && !empty($workspaceStageRecs)) {
             end($workspaceStageRecs);
-            while (!is_null($workspaceStageRecKey = key($workspaceStageRecs))) {
+            while ($workspaceStageRecKey = key($workspaceStageRecs) !== null) {
                 $workspaceStageRec = current($workspaceStageRecs);
                 if ($workspaceStageRec['uid'] == $stageId) {
                     $prevStage = prev($workspaceStageRecs);