Suggestion 12: Locking pragma version to 0.8.24

solidity/contracts/BitcoinDepositor.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-3.0-only
-pragma solidity ^0.8.21;
+pragma solidity 0.8.24;
 
 import "@openzeppelin/contracts-upgradeable/access/Ownable2StepUpgradeable.sol";
 import {SafeERC20} from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

solidity/contracts/BitcoinRedeemer.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-3.0-only
-pragma solidity ^0.8.21;
+pragma solidity 0.8.24;
 
 import "@openzeppelin/contracts-upgradeable/access/Ownable2StepUpgradeable.sol";
 

solidity/contracts/MezoAllocator.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-3.0-only
-pragma solidity ^0.8.21;
+pragma solidity 0.8.24;
 
 import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
 import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

solidity/contracts/PausableOwnable.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-3.0-only
-pragma solidity ^0.8.21;
+pragma solidity 0.8.24;
 
 import "@openzeppelin/contracts-upgradeable/utils/PausableUpgradeable.sol";
 import "@openzeppelin/contracts-upgradeable/access/Ownable2StepUpgradeable.sol";

solidity/contracts/bridge/ITBTCToken.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-3.0-only
-pragma solidity ^0.8.21;
+pragma solidity 0.8.24;
 
 /// @title Interface of TBTC token contract.
 /// @notice This interface defines functions of TBTC token contract used by Acre

solidity/contracts/interfaces/IDispatcher.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-3.0-only
-pragma solidity ^0.8.21;
+pragma solidity 0.8.24;
 
 /// @title IDispatcher
 /// @notice Interface for the Dispatcher contract.

solidity/contracts/lib/ERC4626Fees.sol

@@ -2,7 +2,7 @@
 
 // Inspired by https://docs.openzeppelin.com/contracts/5.x/erc4626#fees
 
-pragma solidity ^0.8.21;
+pragma solidity 0.8.24;
 
 import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
 import {ERC4626Upgradeable} from "@openzeppelin/contracts-upgradeable/token/ERC20/extensions/ERC4626Upgradeable.sol";

solidity/contracts/stBTC.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-3.0-only
-pragma solidity ^0.8.21;
+pragma solidity 0.8.24;
 
 import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
 

solidity/contracts/test/BitcoinDepositorHarness.sol

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-3.0-only
 /* solhint-disable func-name-mixedcase */
-pragma solidity ^0.8.21;
+pragma solidity 0.8.24;
 
 import {BitcoinDepositor} from "../BitcoinDepositor.sol";
 import {MockBridge, MockTBTCVault} from "@keep-network/tbtc-v2/contracts/test/TestTBTCDepositor.sol";

solidity/contracts/test/MezoPortalStub.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-3.0
-pragma solidity ^0.8.21;
+pragma solidity 0.8.24;
 
 import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
 import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

solidity/contracts/test/TestERC20.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-3.0-only
-pragma solidity ^0.8.21;
+pragma solidity 0.8.24;
 
 import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
 

solidity/contracts/test/TestTBTC.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-3.0-only
-pragma solidity ^0.8.21;
+pragma solidity 0.8.24;
 
 import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
 import "../bridge/ITBTCToken.sol";

solidity/contracts/test/upgrades/BitcoinDepositorV2.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-3.0-only
-pragma solidity ^0.8.21;
+pragma solidity 0.8.24;
 
 import "@openzeppelin/contracts-upgradeable/access/Ownable2StepUpgradeable.sol";
 import {SafeERC20} from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

solidity/contracts/test/upgrades/MezoAllocatorV2.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-3.0-only
-pragma solidity ^0.8.21;
+pragma solidity 0.8.24;
 
 import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
 import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

solidity/contracts/test/upgrades/stBTCV2.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-3.0-only
-pragma solidity ^0.8.21;
+pragma solidity 0.8.24;
 
 import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
 

solidity/contracts/utils/Errors.sol

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-3.0-only
 
-pragma solidity ^0.8.21;
+pragma solidity 0.8.24;
 
 /// @notice Reverts if a checked address is zero. Used by various contracts.
 error ZeroAddress();

solidity/hardhat.config.ts

@@ -32,7 +32,7 @@ const config: HardhatUserConfig = {
   solidity: {
     compilers: [
       {
-        version: "0.8.21",
+        version: "0.8.24",
         settings: {
           optimizer: {
             enabled: true,

solidity/package.json

@@ -50,7 +50,7 @@
     "dotenv-safer": "^1.0.0",
     "eslint": "^8.54.0",
     "ethers": "^6.8.1",
-    "hardhat": "^2.19.1",
+    "hardhat": "^2.22.3",
     "hardhat-contract-sizer": "^2.10.0",
     "hardhat-deploy": "^0.11.43",
     "hardhat-gas-reporter": "^1.0.9",