Spanish Months are not correct

Imported from https://gitlab.com/rilian-la-te/musl-locales/-/issues/10.

Author: Charles Bochet (@charlesBochet).

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Hi!

Thanks for maintaining this repository! I'm using the es_ES locale and I've spotted two important mistakes:

bash-5.0$ export LANG='es_ES.UTF-8'
bash-5.0$ locale -k LC_TIME
abday="dom;lun;mar;mie;jue;vie;sab"
day="domingo;lunes;martes;miercoles;jueves;viernes;sabado"
abmon="en;feb;mar;abr;may;jun;jul;aug;sep;oct;nov;dec"
mon="enero;febrero;marzo;abril;may;junio;julio;augosto;septiembre;octubre;noviembre;diciembre"
am_pm="AM;PM"
d_t_fmt="%a %b %e %T %Y"
d_fmt="%d-%m-%y"
t_fmt="%H:%M:%S"
era=""
era_d_fmt="%d-%m-%y"
alt_digits="0123456789"
era_d_t_fmt="%a %b %e %T %Y"
era_t_fmt="%H:%M:%S"

==> May should be Mayo and Augosto should be Agosto I believe this is in musl-po/es_ES file.

Thanks! Charles