The Munich Oktoberfest opens on Saturday, with eager fans sprinting towards the beer tents for their first litres at what is considered the largest folk festival in the world. But this year’s party comes shortly after a deadly knife attack at a festival in the western city of Solingen, so security will be tight. Bavarian Interior Minister Joachim Herrmann said there are no specific threats against 189th edition of the iconic two-week celebration that attracted more than 7 million people last year. Still, authorities say they are on high alert. There is a sophisticated security concept for the …