Simplify SunTimeException

This is enough for an expection that just contains
a message ( https://stackoverflow.com/a/1319675 ).

To verify that it works as expected, the TestNoSun tests
are expanded to check the exception message.

suntime/suntime.py

@@ -8,9 +8,7 @@
 
 
 class SunTimeException(Exception):
-
-    def __init__(self, message):
-        super(SunTimeException, self).__init__(message)
+    pass
 
 
 class Sun:

tests.py

@@ -92,12 +92,12 @@ def setUp(self):
 
     def test_get_sunrise_time(self):
         # Test for no sunrise
-        with self.assertRaises(SunTimeException):
+        with self.assertRaisesRegex(SunTimeException, 'The sun'):
             self.sun.get_sunrise_time(datetime(2024, 12, 21))  # Winter solstice in the northern hemisphere
 
     def test_get_sunset_time(self):
         # Test for no sunset
-        with self.assertRaises(SunTimeException):
+        with self.assertRaisesRegex(SunTimeException, 'The sun'):
             self.sun.get_sunset_time(datetime(2024, 6, 21))  # Summer solstice in the northern hemisphere