Fix memory leak

The timer object was not properly removed when elpa_destroy() was called
on an ELPA instance, leading to a memory leak

src/elpa_impl.F90

@@ -2072,6 +2072,7 @@ module elpa_impl
     subroutine elpa_destroy(self)
       use elpa_generated_fortran_interfaces
       class(elpa_impl_t) :: self
+      call timer_free(self%timer)
       call elpa_index_free_c(self%index)
     end subroutine