contracts-bedrock: factory semver bump

Uses the new constant and bumps the semver

packages/contracts-bedrock/semver-lock.json

@@ -29,7 +29,7 @@
   "src/periphery/op-nft/OptimistAllowlist.sol": "0x53e9a9dfecbae036fd468e8f34c80c7d9c35bd8908c8a6483db44dbc5128ad69",
   "src/periphery/op-nft/OptimistInviter.sol": "0xfdd5b9d45205ef9372ba37f7a6394724695e676d27a47cb154ee6e4148490013",
   "src/universal/OptimismMintableERC20.sol": "0x17fe6e955dc7e9e480e57bc62c227206838b204dcb660b8cb8f6f217319a22ba",
-  "src/universal/OptimismMintableERC20Factory.sol": "0xceba817d4e4b27345525d9eaa1ef5e11952439278766b8bb1eb2b97c59fbb587",
+  "src/universal/OptimismMintableERC20Factory.sol": "0x684a9445515e3797722b211e2c0d6a94b6244d6fa028cd2825a31538ef2dc59c",
   "src/universal/OptimismMintableERC721.sol": "0x49dc863caf3e002bf0c90b3af3873990fb282771f4c63735fd61a885b7873983",
   "src/universal/OptimismMintableERC721Factory.sol": "0x502438b009bfaf0ab187914662468261f10446fd85d44a79b29cdaef7b4982ba"
 }
\ No newline at end of file

packages/contracts-bedrock/src/universal/OptimismMintableERC20Factory.sol

@@ -4,6 +4,7 @@ pragma solidity 0.8.15;
 import { OptimismMintableERC20 } from "src/universal/OptimismMintableERC20.sol";
 import { Initializable } from "@openzeppelin/contracts/proxy/utils/Initializable.sol";
 import { ISemver } from "src/universal/ISemver.sol";
+import { Constants } from "src/libraries/Constants.sol";
 
 /// @custom:proxied
 /// @custom:predeployed 0x4200000000000000000000000000000000000012
@@ -31,8 +32,8 @@ contract OptimismMintableERC20Factory is ISemver, Initializable {
     event OptimismMintableERC20Created(address indexed localToken, address indexed remoteToken, address deployer);
 
     /// @notice Semantic version.
-    /// @custom:semver 1.5.0
-    string public constant version = "1.5.0";
+    /// @custom:semver 1.6.0
+    string public constant version = "1.6.0";
 
     /// @notice The semver MUST be bumped any time that there is a change in
     ///         the OptimismMintableERC20 token contract since this contract
@@ -43,7 +44,7 @@ contract OptimismMintableERC20Factory is ISemver, Initializable {
 
     /// @notice Initializer.
     /// @param _bridge Address of the StandardBridge on this chain.
-    function initialize(address _bridge) public reinitializer(2) {
+    function initialize(address _bridge) public reinitializer(Constants.INITIALIZER) {
         bridge = _bridge;
     }