There's a whole protocol for doing exactly this. It's the time zone database/tz/tzinfo and is regularly updated for this very reason. Lots of countries and regions fiddle with their time on a regular basis and every major operating system has been able to accommodate it for decades. You can see a long discussion about managing DST or lack thereof in Egypt and Lebanon in the associated mailing lists just this month.

tzinfo updates usually are packaged into broader OS updates. Getting the right time is just a matter of running Windows Update or whatever other update utility you use. You can even check out the list of all of the DST-specific updates that Microsoft has done here.