Add test source junit 5 and updated the exception

src/test/kotlin/MoneyTests.kt

@@ -0,0 +1,17 @@
+import com.cubetiqs.libra.moneyutils.Money
+import com.cubetiqs.libra.moneyutils.plus
+import com.cubetiqs.libra.moneyutils.times
+import com.cubetiqs.libra.moneyutils.timesAssign
+import org.junit.Assert
+import org.junit.Test
+
+class MoneyTests {
+    @Test
+    fun test() {
+        val money = Money(10.0)
+        val money2 = Money(20.0)
+        money *= money
+        println((money + money2) * money2)
+        Assert.assertEquals(10, 10)
+    }
+}