Cleanup: remove unused import and "using for" (#6080)

Co-authored-by: Hadrien Croubois <hadrien.croubois@gmail.com>

Author: Fibonacci747

contracts/token/ERC1155/extensions/ERC1155URIStorage.sol

@@ -3,16 +3,13 @@
 
 pragma solidity ^0.8.24;
 
-import {Strings} from "../../../utils/Strings.sol";
 import {ERC1155} from "../ERC1155.sol";
 
 /**
  * @dev ERC-1155 token with storage based token URI management.
  * Inspired by the {ERC721URIStorage} extension
  */
 abstract contract ERC1155URIStorage is ERC1155 {
-    using Strings for uint256;
-
     // Optional base URI
     string private _baseURI = "";
 

contracts/token/ERC721/extensions/ERC721URIStorage.sol

@@ -5,16 +5,13 @@ pragma solidity ^0.8.24;
 
 import {ERC721} from "../ERC721.sol";
 import {IERC721Metadata} from "./IERC721Metadata.sol";
-import {Strings} from "../../../utils/Strings.sol";
 import {IERC4906} from "../../../interfaces/IERC4906.sol";
 import {IERC165} from "../../../interfaces/IERC165.sol";
 
 /**
  * @dev ERC-721 token with storage based token URI management.
  */
 abstract contract ERC721URIStorage is IERC4906, ERC721 {
-    using Strings for uint256;
-
     // Interface ID as defined in ERC-4906. This does not correspond to a traditional interface ID as ERC-4906 only
     // defines events and does not include any external function.
     bytes4 private constant ERC4906_INTERFACE_ID = bytes4(0x49064906);