docs: Fix is_birthday example

The example in the documentation asserts that `pendulum.datetime(1987, 4, 23).is_birthday(pendulum.datetime(2014, 2, 23))`, but that is probably just a typo.

Author: palotasb-booking

docs/docs/comparison.md

@@ -64,7 +64,7 @@ the `now()` is created in the same timezone as the instance.
 
 >>> born = pendulum.datetime(1987, 4, 23)
 >>> not_birthday = pendulum.datetime(2014, 9, 26)
->>> birthday = pendulum.datetime(2014, 2, 23)
+>>> birthday = pendulum.datetime(2014, 4, 23)
 >>> past_birthday = pendulum.now().subtract(years=50)
 
 >>> born.is_birthday(not_birthday)