Another global event is causing another run on what many might consider a household necessity, although in this case, some might prefer a toilet paper shortage.For those who love Diet Coke — and there are many — it’s much more than a fizzy brown beverage. It’s a way of life, an obsession and a cultural symbol, with its fans often described as a hardcore cult and Gen Z influencers referring to the drink as a “fridge cigarette.” There’s even a Diet Coke exhibit at the National Museum of American History, in a collection of “national treasures.”So, the mere mention of…