Added private method

Author: the-yash-rajput

src/main/java/com/thealgorithms/maths/PiApproximation.java

@@ -16,6 +16,10 @@
  */
 public class PiApproximation {
 
+    private PiApproximation() {
+        throw new AssertionError("No instances.");
+    }
+
     /**
      * Structure representing a point with coordinates (x, y)
      * where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1.