‘CBS Evening News’ co-anchor John Dickerson is leaving CBS by the end of the year, according to a source.DIckerson will continue to co-anchor the news with Maurice DuBois until he departs, a CBS News spokesperson confirmed. The news comes as CBS News braces for a steep round of layoffs, which are expected to hit this week.Dickerson, 57, took the co-anchor job earlier this year when then-CBS News president Wendy McMahon decided to shake up the struggling news network and oust then-anchor Norah O’Donnell.Dickerson shared the news on Instagram on Monday morning, writing: “At the end of this year, I will...