fix(ready.js): Refactor FS API & CRON JOB

[iLollek]

This Change implements the following things I have found when analyzing the Code:

• The CRON Expression is not correct if you want to run it on a Sunday as the comment says.

'00 00 23 * *7' to '00 00 23 * * 0' (Sunday = 0, not 7)

• The FS API is more robust now since it's Promise-Based (await)

Changed fs.writeFileSync() to await fs.writeFile()