docs: add change log for PR 13493

changes/ee/feat-13493.en.md

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+Upgrade RPC library `gen_rpc` to 3.4.0
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+The default RPC server socket option in `gen_rpc` 3.4.0 has been changed from `true` to `active-100` which should provide back-pressure towards peer nodes when the RPC server is under heavy load.