fix: add private constructor to ConvexHull to satisfy HideUtilityClassConstructor Checkstyle rule

Author: Kavindya-Kariyawasam

src/main/java/com/thealgorithms/geometry/ConvexHull.java

@@ -22,6 +22,10 @@
  * @author Hardvan
  */
 public final class ConvexHull {
+    private ConvexHull() {
+        throw new AssertionError("Cannot instantiate utility class");
+    }
+
     private static boolean checkPointOrientation(Point i, Point j, Point k) {
         int detK = Point.orientation(i, j, k);
         if (detK > 0) {