add storage gaps

contracts/token/ERC1155/ERC1155.sol

@@ -443,4 +443,6 @@ contract ERC1155 is Initializable, Context, ERC165, IERC1155, IERC1155MetadataUR
 
         return array;
     }
+
+    uint256[50] private ______gap;
 }

contracts/token/ERC1155/ERC1155Burnable.sol

@@ -30,4 +30,6 @@ contract ERC1155Burnable is Initializable, ERC1155 {
 
         _burnBatch(account, ids, values);
     }
+
+    uint256[50] private ______gap;
 }

contracts/token/ERC1155/ERC1155Holder.sol

@@ -17,4 +17,6 @@ contract ERC1155Holder is Initializable, ERC1155Receiver {
     function onERC1155BatchReceived(address, address, uint256[] memory, uint256[] memory, bytes memory) public returns (bytes4) {
         return this.onERC1155BatchReceived.selector;
     }
+
+    uint256[50] private ______gap;
 }

contracts/token/ERC1155/ERC1155Receiver.sol

@@ -19,4 +19,6 @@ contract ERC1155Receiver is Initializable, ERC165, IERC1155Receiver {
             ERC1155Receiver(0).onERC1155BatchReceived.selector
         );
     }
+
+    uint256[50] private ______gap;
 }