Create `ishape_last.txt`

Because the program `test_set_max_speed` in tests `Set_max_speed` and
`Set_max_speed_noise` uses the results of program
`test_get_1_outerm`. `test_set_max_speed` opens an SHPC with
`shpc_open`, so it needs ishape_last.txt.

Inst_eddies/Tests/test_get_1_outerm.f90

@@ -98,6 +98,9 @@ program test_get_1_outerm
      e%valid = .true.
      call shpc_create(hshp, shpc_dir = "SHPC", cyclone = cyclone)
      call write_eddy(e, hshp, date, i = 1)
+     open(unit, file = "SHPC/ishape_last.txt", status = "replace", &
+          action = "write")
+     write(unit, fmt = *) 0
      CALL shpc_close(hshp)
      print *, 'Created "SHPC".'
   else