fix setUTCMonth bug

[rayshen]

this.month is the real month, but setUTCMonth value is 0 ~ 11, the setUTCMonth function makes an error when this.month == month

for exp:
in JS
const date = new Date(1647585448570); //2022-03-18
date.getUTCMonth(); // return 2
date.setUTCMonth(3);
date.getUTCMonth(); // return 3

In AS
const date = new Date(1647585448570); //2022-03-18
date.getUTCMonth(); // return 2
date.setUTCMonth(3); // set failed
date.getUTCMonth(); // return 2 error

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[dcodeIO]

Thanks, tracked in #2239 including test updates :)