Unit Tests

- Removed mention of synch.key from all unit tests.  This is an obsolete file.

test/bug.628.t

@@ -50,12 +50,11 @@ my $output = qx{../src/task rc:bug.rc waiting 2>&1};
 like   ($output, qr/1\/1\/2020/ms, 'a b D Y dateformat correctly parsed.');
 
 # Cleanup.
-unlink qw(pending.data completed.data undo.data backlog.data synch.key bug.rc);
+unlink qw(pending.data completed.data undo.data backlog.data bug.rc);
 ok (! -r 'pending.data'   &&
     ! -r 'completed.data' &&
     ! -r 'undo.data'      &&
     ! -r 'backlog.data'   &&
-    ! -r 'synch.key'      &&
     ! -r 'bug.rc', 'Cleanup');
 
 exit 0;