* add a protection mechanism to prevent relaying transaction that are not
part of an execute operation

* more accurate relay authorization

* force reset the relay authorizations after executions

* refactor of the onlyGovernor modifier

* only whitelist when executor is not governor itself

* fix lint

* add private function for call permission management

* use deque

* fix lint

* remove unecessary dependency

* remove unecessary dependency

* comment rephrasing

* Update contracts/governance/Governor.sol

Co-authored-by: Francisco Giordano <frangio.1@gmail.com>

* cache keccak256(_msgData())

* use Context

* lint

* conditionnal clear

* add test to cover queue.clear()

* lint

* write more extended docs for onlyGovernance

* add changelog entry

Co-authored-by: Francisco Giordano <frangio.1@gmail.com>