chore: use fixed variable for contract version (#457)

Author: 0xChin

packages/contracts-bedrock/snapshots/abi/ProposalValidator.json

@@ -538,7 +538,7 @@
         "type": "string"
       }
     ],
-    "stateMutability": "pure",
+    "stateMutability": "view",
     "type": "function"
   },
   {

packages/contracts-bedrock/snapshots/semver-lock.json

@@ -172,8 +172,8 @@
     "sourceCodeHash": "0x9baa0f9e744cc0ecc61d0fade8bffc18321b228833ea0904dc645f3975be9ed1"
   },
   "src/governance/ProposalValidator.sol:ProposalValidator": {
-    "initCodeHash": "0x6bcced3e1050048ecc63fd4d9a86ec72e756de4cb328d29c357cc31c87834341",
-    "sourceCodeHash": "0x9380a09eeb5f12304baf0d45ea14e7bbd1b046d805429bfe0de970a7dfccd176"
+    "initCodeHash": "0x8f58c80a20e9f5e631d9451d86b2b5478a60879e58420f6788e75629f5863430",
+    "sourceCodeHash": "0x1d4ce0d6f868bd36418e7e760c81ecb033c15720e6a35f088ea135620fcae91a"
   },
   "src/legacy/DeployerWhitelist.sol:DeployerWhitelist": {
     "initCodeHash": "0x53099379ed48b87f027d55712dbdd1da7d7099925426eb0531da9c0012e02c29",

packages/contracts-bedrock/src/governance/ProposalValidator.sol

@@ -206,6 +206,10 @@ contract ProposalValidator is OwnableUpgradeable, ReinitializableBase, ISemver {
                                CONSTANTS
     //////////////////////////////////////////////////////////////*/
 
+    /// @notice Semantic version.
+    /// @custom:semver 1.0.0
+    string public constant version = "1.0.0";
+
     /// @notice The divisor used for percentage calculations in optimistic voting modules.
     /// @dev Represents 100% in basis points (10,000 = 100%).
     uint256 public constant OPTIMISTIC_MODULE_PERCENT_DIVISOR = 10_000;
@@ -238,12 +242,6 @@ contract ProposalValidator is OwnableUpgradeable, ReinitializableBase, ISemver {
     /// @notice Mapping of proposal hash to their corresponding proposal data.
     mapping(bytes32 => ProposalData) internal _proposals;
 
-    /// @notice Semantic version.
-    /// @custom:semver 1.0.0
-    function version() public pure virtual returns (string memory) {
-        return "1.0.0";
-    }
-
     /// @notice Constructs the ProposalValidator contract.
     /// @param _approvedProposerAttestationSchemaUid The schema UID for attestations in EAS for submitting proposals.
     /// @param _topDelegatesAttestationSchemaUid The schema UID for attestations in EAS for checking if the caller