dirstate: push back the future a bit in the test

The future was set to 2021-01-01, we push it by 10 years.

tests/test-dirstate.t

@@ -53,13 +53,13 b' Prepare test repo:'
 
 Set mtime of a into the future:
 
-  $ touch -t 202101011200 a
+  $ touch -t 203101011200 a
 
 Status must not set a's entry to unset (issue1790):
 
   $ hg status
   $ hg debugstate
-  n 644          2 2021-01-01 12:00:00 a
+  n 644          2 2031-01-01 12:00:00 a
 
 Test modulo storage/comparison of absurd dates: