Bump minimum Solidity version for Initializable.sol to 0.8.2 (#3328)

contracts/proxy/utils/Initializable.sol

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 // OpenZeppelin Contracts (last updated v4.5.0) (proxy/utils/Initializable.sol)
 
-pragma solidity ^0.8.0;
+pragma solidity ^0.8.2;
 
 import "../../utils/Address.sol";