* replace `immutable` with `constant` for _PERMIT_TYPEHASH

This commit is related to the following issue discussion: https://github.com/OpenZeppelin/contracts-wizard/issues/89#issuecomment-1042391318

Since Solidity version `0.6.12` the `keccak256` of string literals is treated specially and the hash is evaluated at compile time. Since the OpenZeppelin Wizard also uses `constant` for OpenZeppelin's AccessControl's roles declarations, it's good practice to make this consistent.

* Update CHANGELOG

* fix: ensure transpiler compatibility

* fix: fixing var-name-mixedcase

* prettier & lint check

Signed-off-by: Pascal Marco Caversaccio <pascal.caversaccio@hotmail.ch>

Co-authored-by: Hadrien Croubois <hadrien.croubois@gmail.com>

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

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

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

Fix camelcase of 'lastvalue' to 'lastValue'

Co-authored-by: Renovate Bot <bot@renovateapp.com>

Co-authored-by: Renovate Bot <bot@renovateapp.com>

Co-authored-by: Hadrien Croubois <hadrien.croubois@gmail.com>

Co-authored-by: Renovate Bot <bot@renovateapp.com>

Fix misspelling in ERC20 contract comments.

* 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>

Co-authored-by: Renovate Bot <bot@renovateapp.com>

* add vector, lifo and fifo structures

* fix lint

* need more memory for coverage

* remove Vector wrappers and gas optimization

* refactor Vector testing

* revert package.json changes

* rename to DoubleEndedQueue

* rename and refactor

* refactor tests and expand coverage

* test for custom errors

* add changelog entry

* add docs

* add sample code and note about storage vs. memory

* add available since

* lint

* use underscore for struct members

* add struct documentation

* remove SafeCast in length

* rename i -> index and improve docs

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