Removes unreachable case in retrieving remote port value

The _ case would never match, as the previous clause would cover all cases being returned from Plug.Conn.get_peer_data(conn). The dialyzer warning:

```
lib/sentry/plug.ex:187: The variable _ can never match since previous clauses completely covered the type #{'address':={byte(),byte(),byte(),byte()} | {char(),char(),char(),char(),char(),char(),char(),char()}, 'port':=char(), 'ssl_cert':='nil' | binary()}
```

When removing that default case, the need for the case statement disappeared, and we can just fetch the remote port inline on LN174 instead.

Author: heymackey

lib/sentry/plug.ex

@@ -171,24 +171,14 @@ if Code.ensure_loaded?(Plug) do
         headers: handle_data(conn, header_scrubber),
         env: %{
           "REMOTE_ADDR" => remote_address(conn.remote_ip),
-          "REMOTE_PORT" => remote_port(conn),
+          "REMOTE_PORT" => Plug.Conn.get_peer_data(conn).port,
           "SERVER_NAME" => conn.host,
           "SERVER_PORT" => conn.port,
           "REQUEST_ID" => Plug.Conn.get_resp_header(conn, request_id) |> List.first()
         }
       }
     end
 
-    defp remote_port(conn) do
-      case Plug.Conn.get_peer_data(conn) do
-        %{port: port} ->
-          port
-
-        _ ->
-          ""
-      end
-    end
-
     defp remote_address(address) do
       address
       |> :inet.ntoa()