OTTAWA—Work is underway for a travel exemption that would let the winner of the NHL’s all-Canadian division and an American counterpart cross the border during the third and final rounds of the playoffs. Two federal government sources say the exemption would let teams still in the Stanley Cup hunt enter Canada for games without having to isolate for 14 days, as is currently required for all non-essential travellers entering the country. The sources, who were granted anonymity because they aren’t authorized to speak publicly, say the NHL has been working to secure approval from public health authorities in the provinces and cities that still have teams in the playoffs. Once those signatures are collected, the request will go to federal Immigration Minister Marco Mendicino for final approval. A league spokesperson said the NHL still is awaiting answers from governments. In an email to The Canadian Press, NHL deputy commissioner Bill …