The Milwaukee Brewers made it three in a row over the Chicago Cubs and four straight overall with a 3-1 victory at Wrigley Field Wednesday night.   With the game tied at one, the Brewers ran their way to a pair of runs in the top of the 7th.  Nyjer Morgan got it going with a bunt single and scampered to second on a wild throw to first.   Jean Segura then drove Morgan home with a single.   When Segura stole second base, the Cubs misplayed the throw, Segura charged to third and another throw got away, allowing him to stroll home.   The three errors in a matter of minutes was too much to overcome and it allowed Mark Fiers to pick up his 8th win of the year.  The rookie went seven and a third innings, allowing a run and striking out 6 to improve to 8-6.  John Axford closed out the ninth for his 22nd save.   MIlwaukee (62-67) will try to finish off the sweep and run their winning streak against the Cubs to eight straight games in the series finale Thursday afternoon.