ci: pin ssl_verify_fun in mix.exs

mix.exs

@@ -95,7 +95,9 @@ defmodule EMQXUmbrella.MixProject do
        github: "emqx/ranch", ref: "de8ba2a00817c0a6eb1b8f20d6fb3e44e2c9a5aa", override: true},
       # in conflict by grpc and eetcd
       {:gpb, "4.19.7", override: true, runtime: false},
-      {:hackney, github: "emqx/hackney", tag: "1.18.1-1", override: true}
+      {:hackney, github: "emqx/hackney", tag: "1.18.1-1", override: true},
+      # set by hackney (dependency)
+      {:ssl_verify_fun, "1.1.6", override: true}
     ] ++
       emqx_apps(profile_info, version) ++
       enterprise_deps(profile_info) ++ bcrypt_dep() ++ jq_dep() ++ quicer_dep()