merge method
Implementation
ZeroCheckboxStyle merge(ZeroCheckboxStyle? other) {
if (other == null) return this;
return copyWith(
activeColor: other.activeColor,
disabledColor: other.disabledColor,
checkColor: other.checkColor,
inactiveColor: other.inactiveColor,
borderRadius: other.borderRadius,
borderSize: other.borderSize,
);
}