"text" values should be skipped when signing

[Matheus28]

See how this other repo does it: https://github.com/Talv/sc2-repdump/blob/e31dede06512d7b3e445b96327102defe28083a2/s2repdump/bank.py#L92

After changing this, I'm able to sign bank files with signatures that match the game.