truffle-config.js

 const HDWalletProvider = require('@truffle/hdwallet-provider');
 //
 const fs = require('fs');
 const mnemonic = fs.readFileSync(".secret").toString().trim();

module.exports = {

  networks: {
    goerli: {
      provider: () => new HDWalletProvider(mnemonic, `https://goerli.infura.io/v3/`),
      network_id: 5,       // Ropsten's id
      gas: 5500000,        // Ropsten has a lower block limit than mainnet
      confirmations: 2,    // # of confs to wait between deployments. (default: 0)
      timeoutBlocks: 200,  // # of blocks before a deployment times out  (minimum/default: 50)
      skipDryRun: true     // Skip dry run before migrations? (default: false for public nets )
      },
  },

  // Set default mocha options here, use special reporters etc.
  mocha: {
    // timeout: 100000
  },

  compilers: {
    solc: {
      version: "0.6.10",    // Fetch exact version from solc-bin (default: truffle's version)
      // docker: true,        // Use "0.5.1" you've installed locally with docker (default: false)
      settings: {          // See the solidity docs for advice about optimization and evmVersion
       optimizer: {
         enabled: true,
         runs: 200
       },
       evmVersion: "istanbul"
      }
    }
  },
};