Seven-time Olympic champion Allyson Felix will retire at th end of the current athletic’s season, the US sprint great said on social media Wednesday. “I have given everything I have to running and for the first time I’m not sure if I have anything left to give,” the 36-year-old said. “I want to say goodbye and thank you to the sport and people who have helped shape me the only way I know how—with one last run. This season isn’t about the time on the clock, it’s simply about joy.” Felix took 400-metre bronze and 4x400m relay gold at the delayed 2020 Olympic Games in Tokyo last year. And she cou…