Simplify returns

Author: carusogabriel

src/PhpSpreadsheet/Shared/TimeZone.php

@@ -23,11 +23,7 @@ class TimeZone
      */
     private static function validateTimeZone($timezone)
     {
-        if (in_array($timezone, DateTimeZone::listIdentifiers())) {
-            return true;
-        }
-
-        return false;
+        return in_array($timezone, DateTimeZone::listIdentifiers());
     }
 
     /**

src/PhpSpreadsheet/Worksheet/Worksheet.php

@@ -1469,11 +1469,7 @@ public function getConditionalStyles($pCoordinate)
      */
     public function conditionalStylesExists($pCoordinate)
     {
-        if (isset($this->conditionalStylesCollection[strtoupper($pCoordinate)])) {
-            return true;
-        }
-
-        return false;
+        return isset($this->conditionalStylesCollection[strtoupper($pCoordinate)]);
     }
 
     /**