Remove trailing spaces from BinaryTreeSort

- Fix checkstyle violations on lines 30, 38, 42
- Remove trailing whitespace for compliance
- No functional changes

Author: PauLopNun

src/main/java/com/thealgorithms/sorts/BinaryTreeSort.java

@@ -27,19 +27,19 @@ public <T extends Comparable<T>> T[] sort(T[] array) {
         if (array == null || array.length <= 1) {
             return array;
         }
-        
+
         TreeNode<T> root = null;
         for (T value : array) {
             root = insert(root, value);
         }
 
         List<T> result = new ArrayList<>();
         inorder(root, result);
-        
+
         for (int i = 0; i < array.length; i++) {
             array[i] = result.get(i);
         }
-        
+
         return array;
     }