feat: Ownable2StepUpgradeable to OwnableUpgradeable

This allows the contract to transfer ownership to address 0x000...000 as defined in waku-org/specs#34: `At some point, the _Owner_ SHOULD renounce their privileges, and the contract MUST become immutable`. The problem with `Ownable2StepUpgradeable` is that it requires accepting the ownership transfer, which is not possible with address 0x0

src/LinearPriceCalculator.sol

@@ -1,21 +1,21 @@
 // SPDX-License-Identifier: MIT
 pragma solidity 0.8.24;
 
-import { Ownable2Step } from "openzeppelin-contracts/contracts/access/Ownable2Step.sol";
+import { Ownable } from "openzeppelin-contracts/contracts/access/Ownable.sol";
 import { IPriceCalculator } from "./IPriceCalculator.sol";
 
 /// Address 0x0000...0000 was used instead of an ERC20 token address
 error OnlyTokensAllowed();
 
 /// @title Linear Price Calculator to determine the price to acquire a membership
-contract LinearPriceCalculator is IPriceCalculator, Ownable2Step {
+contract LinearPriceCalculator is IPriceCalculator, Ownable {
     /// @notice Address of the ERC20 token accepted by this contract.
     address public token;
 
     /// @notice The price per message per epoch
     uint256 public pricePerMessagePerEpoch;
 
-    constructor(address _token, uint256 _pricePerMessagePerEpoch) Ownable2Step() {
+    constructor(address _token, uint256 _pricePerMessagePerEpoch) Ownable() {
         _setTokenAndPrice(_token, _pricePerMessagePerEpoch);
     }
 

src/WakuRlnV2.sol

@@ -4,7 +4,7 @@ pragma solidity 0.8.24;
 import { LazyIMT, LazyIMTData } from "@zk-kit/imt.sol/LazyIMT.sol";
 import { PoseidonT3 } from "poseidon-solidity/PoseidonT3.sol";
 
-import { Ownable2StepUpgradeable } from "@openzeppelin/contracts-upgradeable/access/Ownable2StepUpgradeable.sol";
+import { OwnableUpgradeable } from "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
 import { Initializable } from "@openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol";
 import { UUPSUpgradeable } from "@openzeppelin/contracts-upgradeable/proxy/utils/UUPSUpgradeable.sol";
 
@@ -20,7 +20,7 @@ error InvalidIdCommitment(uint256 idCommitment);
 /// Invalid pagination query
 error InvalidPaginationQuery(uint256 startIndex, uint256 endIndex);
 
-contract WakuRlnV2 is Initializable, Ownable2StepUpgradeable, UUPSUpgradeable, MembershipUpgradeable {
+contract WakuRlnV2 is Initializable, OwnableUpgradeable, UUPSUpgradeable, MembershipUpgradeable {
     /// @notice The Field
     uint256 public constant Q =
         21_888_242_871_839_275_222_246_405_745_257_275_088_548_364_400_416_034_343_698_204_186_575_808_495_617;

test/WakuRlnV2.t.sol

@@ -668,8 +668,7 @@ contract WakuRlnV2Test is Test {
 
         /*| Name                | Type                                                | Slot | Offset | Bytes |
           |---------------------|-----------------------------------------------------|------|--------|-------|
-          | nextFreeIndex | uint32                                              | 256  | 0      | 4     | */
-
+          | nextFreeIndex       | uint32                                              | 206  | 0      | 4     | */
         /*
         Pro tip: to easily find the storage slot of a variable, without having to calculate the storage layout
         based on the variable declaration, set the variable to an easily grepable value like 0xDEADBEEF, and then
@@ -687,7 +686,7 @@ contract WakuRlnV2Test is Test {
         */
 
         // we set nextFreeIndex to 4294967295 (1 << 20) = 0x00100000
-        vm.store(address(w), bytes32(uint256(256)), 0x0000000000000000000000000000000000000000000000000000000000100000);
+        vm.store(address(w), bytes32(uint256(206)), 0x0000000000000000000000000000000000000000000000000000000000100000);
         token.approve(address(w), price);
         vm.expectRevert(bytes("Membership set is full"));
         w.register(1, membershipRateLimit);