chore: bump `ehttpc` to 0.4.14

Which includes a fix that prevents `emqtt_pool` from reusing pools
in an inconsistent state.

mix.exs

@@ -49,7 +49,7 @@ defmodule EMQXUmbrella.MixProject do
       {:redbug, github: "emqx/redbug", tag: "2.0.10"},
       {:covertool, github: "zmstone/covertool", tag: "2.0.4.1", override: true},
       {:typerefl, github: "ieQu1/typerefl", tag: "0.9.1", override: true},
-      {:ehttpc, github: "emqx/ehttpc", tag: "0.4.13", override: true},
+      {:ehttpc, github: "emqx/ehttpc", tag: "0.4.14", override: true},
       {:gproc, github: "emqx/gproc", tag: "0.9.0.1", override: true},
       {:jiffy, github: "emqx/jiffy", tag: "1.0.6", override: true},
       {:cowboy, github: "emqx/cowboy", tag: "2.9.2", override: true},

rebar.config

@@ -77,7 +77,7 @@
     {gpb, "4.19.9"},
     {typerefl, {git, "https://github.com/ieQu1/typerefl", {tag, "0.9.1"}}},
     {gun, {git, "https://github.com/emqx/gun", {tag, "1.3.11"}}},
-    {ehttpc, {git, "https://github.com/emqx/ehttpc", {tag, "0.4.13"}}},
+    {ehttpc, {git, "https://github.com/emqx/ehttpc", {tag, "0.4.14"}}},
     {gproc, {git, "https://github.com/emqx/gproc", {tag, "0.9.0.1"}}},
     {jiffy, {git, "https://github.com/emqx/jiffy", {tag, "1.0.6"}}},
     {cowboy, {git, "https://github.com/emqx/cowboy", {tag, "2.9.2"}}},