minor fix

Co-authored-by: Andrii Siriak <[email protected]>

Author: albina-astr

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

@@ -5,7 +5,7 @@
 import org.junit.jupiter.api.Test;
 
 public class FactorialTest {
-    private static final String EXCEPTION_MESSAGE = "Input number cannot be negative!";
+    private static final String EXCEPTION_MESSAGE = "Input number cannot be negative";
 
     @Test
     public void testWhenInvalidInoutProvidedShouldThrowException() {