While the world celebrates the Boston Police Department’s heroism during the Marathon bombings, TNT has renewed executive producer Donnie Wahlberg’s passion project, “Boston’s Finest.’’ The unscripted series, a personal but respectful look at individual men and women in the BPD, will be back for a second season early next year. Wahlberg provides the matter-of-fact narration on the show, as we follow patrol officers, detectives, and gang unit and SWAT team members both on and off the clock. The creatively strong and non-stagey eight-episode first season brought in an average of 1.3 million viewers a week. While that’s not a particularly good number for TNT, the show’s prestige, especially after Boston has been in the national news in recent weeks, has proven irresistible. Also, the network is only ordering six episodes this time around and, as part of the deal, CNN, which is one of TNT’s sister channels, will get to encore the episodes each week. So far, “Boston’s Finest’’ is the only one of the three 2013 Boston-based reality series to get any love. The spectacularly awful “Wicked Single’’ on VH1 and the even worse “Southie Rules’’ on A&E have been ratings flops and renewal is unlikely. And I don’t think Bostonians will be mounting social media campaigns to save them.