fix relx git lock with latest commit

rebar.lock

@@ -10,8 +10,7 @@
  {<<"providers">>,{pkg,<<"providers">>,<<"1.8.1">>},0},
  {<<"relx">>,
   {git,"https://github.com/erlware/relx.git",
-       {ref,"aa6c81d265986f223fa347cacf3b9691e7b56f2f"},
-       []},
+       {ref,"aa6c81d265986f223fa347cacf3b9691e7b56f2f"}},
   0},
  {<<"ssl_verify_fun">>,{pkg,<<"ssl_verify_fun">>,<<"1.1.5">>},0}]}.
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