Bump minimum pragma version to 0.8.19 (#4288)

docs/modules/ROOT/pages/index.adoc

@@ -26,7 +26,7 @@ Once installed, you can use the contracts in the library by importing them:
 ----
 // contracts/MyNFT.sol
 // SPDX-License-Identifier: MIT
-pragma solidity ^0.8.0;
+pragma solidity ^0.8.19;
 
 import "@openzeppelin/contracts/token/ERC721/ERC721.sol";