fix(utime.c): set_time should operate in local tz

Needed due to changes from 8c59935e.

cc !146 (closed)

cc @rahix @schneider

Documentation/pycardium/utime.rst

@@ -25,11 +25,13 @@ alarm.
 
 .. py:function:: time()
 
-   Return the current timestamp in seconds since 2000-01-01 00:00.
+   Return the current timestamp in seconds since 2000-01-01 00:00 in
+   the local timezone.
 
 .. py:function:: set_time(secs)
 
-   Sets the time to ``secs`` seconds since 2000-01-01 00:00.
+   Sets the time to ``secs`` seconds since 2000-01-01 00:00 in the local
+   timezone.
    
 .. py:function:: set_unix_time(secs)