fix(proxy): chunked encoding mustn't set content-length header

lib/web/proxy/reverse_proxy.ex

@@ -187,9 +187,13 @@ defmodule Mobilizon.Web.ReverseProxy do
   @spec response(Plug.Conn.t(), any(), String.t(), pos_integer(), list(tuple()), Keyword.t()) ::
           Plug.Conn.t()
   defp response(conn, client, url, status, headers, opts) do
+    headers = build_resp_headers(headers, opts)
+    # Fix HTTP/1.1 protocol violation: content-length can't be combined with chunked encoding
+    headers = Enum.reject(headers, fn {k, _} -> k == "content-length" end)
+
     result =
       conn
-      |> put_resp_headers(build_resp_headers(headers, opts))
+      |> put_resp_headers(headers)
       |> send_chunked(status)
       |> chunk_reply(client, opts)