Support for flat config files

[flipflop97]

When importing this molule in a now-required flat config file, I get the following error:

Error: This method cannot be used with flat config. Add your entries directly into the config array.
    at assertEslintrcConfig (REPO/node_modules/eslint/lib/linter/linter.js:1286:15)
    at Linter.getRules (REPO/node_modules/eslint/lib/linter/linter.js:2215:9)
    at Object.<anonymous> (REPO/node_modules/eslint-plugin-sonar/lib/index.cjs:193:60)
    at Module._compile (node:internal/modules/cjs/loader:1375:14)
    at Module._extensions..js (node:internal/modules/cjs/loader:1434:10)
    at Module.load (node:internal/modules/cjs/loader:1206:32)
    at Module._load (node:internal/modules/cjs/loader:1022:12)
    at Module.require (node:internal/modules/cjs/loader:1234:19)
    at require (node:internal/modules/helpers:176:18)
    at Object.<anonymous> (REPO/eslint.config.js:5:27)

Using:

"eslint": "9.0.0",
"eslint-plugin-sonar": "0.13.2"