Fix test

Author: geoperez

test/Unosquare.DateTimeExt.Test/Unosquare.DateTimeExt.Test/YearEntity-Tests.cs

@@ -27,15 +27,15 @@ public void WithYear_ReturnsNextYear()
     {
         ILinkedEntity<IHasReadOnlyYear> result = new YearEntity(2023);
 
-        Assert.Equal(2024, result.Next.Year);
+        Assert.Equal(2024, result.Next().Year);
     }
 
     [Fact]
     public void WithYear_ReturnsPreviousYear()
     {
         var result = new YearEntity(2023);
 
-        Assert.Equal(2022, result.Previous.Year);
+        Assert.Equal(2022, result.Previous().Year);
     }
 
     [Fact]