config eslint-plugin-relay with flat-config

[timble-one]

https://github.com/relayjs/eslint-plugin-relay

Haven't managed that yet. That's why eslint is still on v8. It's not so bad, because dev-dependency.
But there are several deprecation warnings because of the outdated eslint version.

I allready opened an issue on the plugin: relayjs/eslint-plugin-relay#156

It looks like eslint v8 only supports up to typescript v5.6 For this reason, typescript is fixed to v5.6