Fix wrong register assignment

[rkaustchr]

Fixed the the wrong assignment for the register $v0 on the exercises:

Registor Color
Registor Color Duo
Scrabble Score

[github-actions]

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[rkaustchr]

Link of the discussion on the forum: https://forum.exercism.org/t/wrong-assign-register-in-the-resistor-color-exercise-mips-track/8286

[keiravillekode]

lgtm

[ErikSchierboom]

Good catch