clock: update to version 2.4.0 (#870)

exercism/problem-specifications#1400
test case for exactly negative sixty minutes

Author: tejasbubane

exercises/clock/package.yaml

@@ -1,5 +1,5 @@
 name: exercism-clock
-version: 2.3.0.8
+version: 2.4.0.9
 
 dependencies:
   - base

exercises/clock/test/Tests.hs

@@ -52,6 +52,7 @@ specs = do
       , ("negative minutes"                                     ,    1,   -40, "00:20")
       , ("negative minutes roll over"                           ,    1,  -160, "22:20")
       , ("negative minutes roll over continuously"              ,    1, -4820, "16:40")
+      , ("negative sixty minutes is previous hour"              ,    2,   -60, "01:00")
       , ("negative hour and minutes both roll over"             ,  -25,  -160, "20:20")
       , ("negative hour and minutes both roll over continuously", -121, -5810, "22:10") ]