Epic Games: fix `getOfferedGames`, endpoint and API changed

[Purexo]

It seems they changed the endpoint and API 😬
https://store.epicgames.com/graphql

Originally posted by @Purexo in #106 (comment)

Need to take time to reverse engine and find proper way to get free games list.

[targos]

I just made a quick test locally, and it seems that the new URL is protected by Cloudflare. I get HTML with a captcha :(

[Purexo]

https://github.com/FlareSolverr/FlareSolverr

I have this on my infra, we could give it a try for the bot

[Purexo]

https://store-site-backend-static.ak.epicgames.com/freeGamesPromotions