How to manage different version of solidity compilers in smart contract?

Question

• source.sol

    pragma solidity >=0.7.0 <=0.8.4;
    
    import "@chainlink/contracts/src/v0.7/ChainlinkClient.sol";
    import "@openzeppelin/contracts/access/Ownable.sol";
    import "@openzeppelin/contracts/utils/Strings.sol";

• hardhat.config.ts

      solidity: {
        compilers: [
          { version: "0.8.4", },
          { version: "0.8.0", },
          { version: "0.7.0", settings: {}, },
          { version: "0.6.0", },
        ],
      },

Error HH606: The project cannot be compiled, see reasons below.

These files and its dependencies cannot be compiled with your config. This can happen because they have incompatible Solidity pragmas, or don't match any of your configured Solidity compilers.

To learn more, run the command again with --verbose

Read about compiler configuration at https://hardhat.org/config