Update solidity to 0.8.23

contracts/Configuration.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-pragma solidity ^0.8.8;
+pragma solidity 0.8.23;
 
 import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
 

contracts/Endian.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-pragma solidity ^0.8.8;
+pragma solidity 0.8.23;
 
 contract Endian {
   /// reverses byte order to allow conversion between little endian and big

contracts/Groth16.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-pragma solidity ^0.8.8;
+pragma solidity 0.8.23;
 
 struct G1Point {
     uint x;

contracts/Marketplace.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-pragma solidity ^0.8.8;
+pragma solidity 0.8.23;
 
 import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
 import "@openzeppelin/contracts/utils/math/Math.sol";

contracts/Periods.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-pragma solidity ^0.8.8;
+pragma solidity 0.8.23;
 
 contract Periods {
   type Period is uint256;

contracts/Proofs.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-pragma solidity ^0.8.8;
+pragma solidity 0.8.23;
 
 import "./Configuration.sol";
 import "./Requests.sol";

contracts/Requests.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-pragma solidity ^0.8.8;
+pragma solidity 0.8.23;
 
 type RequestId is bytes32;
 type SlotId is bytes32;

contracts/StateRetrieval.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-pragma solidity ^0.8.8;
+pragma solidity 0.8.23;
 
 import "@openzeppelin/contracts/utils/structs/EnumerableSet.sol";
 import "./Requests.sol";

contracts/TestVerifier.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-pragma solidity ^0.8.8;
+pragma solidity 0.8.23;
 
 import "./Verifier.sol";
 

contracts/Verifier.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-pragma solidity ^0.8.8;
+pragma solidity 0.8.23;
 
 interface IVerifier {
   function verifyProof(

contracts/verifiers/local/verifier_groth.sol

@@ -17,7 +17,7 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 // SPDX-License-Identifier: MIT
-pragma solidity ^0.8.8;
+pragma solidity 0.8.23;
 library Pairing {
     struct G1Point {
         uint X;

hardhat.config.js

@@ -4,7 +4,7 @@ require("hardhat-deploy-ethers")
 
 module.exports = {
   solidity: {
-    version: "0.8.8",
+    version: "0.8.23",
     settings: {
       optimizer: {
         enabled: true,

verifier/template/verifier_groth.sol

@@ -17,7 +17,7 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 // SPDX-License-Identifier: MIT
-pragma solidity ^0.8.8;
+pragma solidity 0.8.23;
 library Pairing {
     struct G1Point {
         uint X;