added private contructor

Author: DarkMatter-999

src/main/java/com/thealgorithms/bitmanipulation/NumberAppearingOddTimes.java

@@ -6,6 +6,8 @@
  */
 
 public class NumberAppearingOddTimes {
+    private NumberAppearingOddTimes() {
+    }
     public static int findOddOccurrence(int[] arr) {
         int result = 0;