Voters in Massachusetts’s 5th congressional district have the opportunity to take to the polls today to fill the seat vacated by Edward J. Markey (D), who became a senator in July. Haven’t heard of today’s election? Well, don’t be too hard on yourself. “Even in the district, you’re not hearing much about it,” Jon Keller, a political analyst at Boston’s WBZ-TV tells The Post’s Chris Cillizza. Why? Well, election fatigue, for one. It’s also taking place in a region that was just recently redistricted, so even voters there may not realize it’s going on. Watch the three-minute interview with Keller to get caught up to speed on who will become the newest member of the House of Representatives.