Fails on TS 5.0 tsconfig where extends field is array

```
TypeError [ERR_INVALID_ARG_TYPE]: The "path" argument must be of type string. Received an instance of Array
    at new NodeError (node:internal/errors:399:5)
    at validateString (node:internal/validators:163:11)
    at Object.isAbsolute (node:path:1161:5)
    at resolveTsConfigFromExtends (.../load-tsconfig/dist/index.cjs:150:27)
```