fix: Remove Extra Mage Reaction

[Sturlen]

Fix after bug report from Trick on the Discord:

Need to remove the spell Misty Step from the reactions of the Mage in the Level Up A5E Monsterous Menagerie.
Found on Page 482 of said book.
https://discord.com/channels/470638316103008268/1166787857625657424

[augustjohnson]

This has been pulled into #383 which is is preparation of the release 1.4.0

[augustjohnson]

This has NOT been fixed as of this:
https://api-beta.open5e.com/v1/monsters/mage-a5e/
It should be a pretty simple fix though, look for mage-a5e in https://github.com/open5e/open5e-api/blob/staging/data/v1/menagerie/Monster.json

[Sturlen]

This seems to be a more widespread issue, not an isolated incident. See issue #393. I'll be closing this and instead look at a more general solution.