chore: final formatting and test fix for BigInteger

Author: VanshSharma3

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

@@ -6,12 +6,6 @@ public final class Factorial {
     private Factorial() {
     }
 
-    /**
-     * Calculate factorial N using iteration
-     *
-     * @param n the number
-     * @return the factorial of {@code n}
-     */
     public static BigInteger factorial(int n) {
         if (n < 0) {
             throw new IllegalArgumentException("Input number cannot be negative");
@@ -22,4 +16,4 @@ public static BigInteger factorial(int n) {
         }
         return result;
     }
-}
+}

src/test/java/com/thealgorithms/maths/FactorialTest.java

@@ -2,9 +2,7 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
-
 import java.math.BigInteger;
-
 import org.junit.jupiter.api.Test;
 
 public class FactorialTest {