Un-public a function which didn't need it

Signed-off-by: Ambre Austen Suhamy <[email protected]>

Author: ElectreAAS

bin/rpc/rpc_common.mli

@@ -18,8 +18,6 @@ val request_exn
 (** Cmdliner term for a generic RPC client. *)
 val client_term : Common.Builder.t -> (unit -> 'a Fiber.t) -> 'a
 
-val establish_client_session : wait:bool -> Dune_rpc_client.Client.Connection.t Fiber.t
-
 (** Cmdliner argument for a wait flag. *)
 val wait_term : bool Cmdliner.Term.t