fix: add ehttpc as emqx_bridge_http dependency

apps/emqx_bridge_http/src/emqx_bridge_http.app.src

@@ -2,7 +2,7 @@
     {description, "EMQX HTTP Bridge and Connector Application"},
     {vsn, "0.1.1"},
     {registered, []},
-    {applications, [kernel, stdlib, emqx_connector, emqx_resource, emqx_bridge]},
+    {applications, [kernel, stdlib, emqx_connector, emqx_resource, emqx_bridge, ehttpc]},
     {env, []},
     {modules, []},
     {links, []}