Change the value of `n_max_cont`

We are going to read `cont_list` from the results of
`test_get_1_outerm` so we want the value of `n_max_cont` to be the
same.

Inst_eddies/Tests/test_set_max_speed.f90

@@ -34,7 +34,7 @@ program test_set_max_speed
   real corner_window(2) ! longitude and latitude of the window around
   ! the extremum, in rad
 
-  integer, parameter:: n_max_cont = 3
+  integer, parameter:: n_max_cont = 31
 
   type(ssh_contour) cont_list(n_max_cont)
   ! Contour list. The outermost contour is element with subscript