The sitting president of the United States has tested positive for COVID-19 once again. President Joe Biden was scheduled to speak at a Las Vegas conference Wednesday night. At the last minute, he called ahead to let attendees know he would not be attending due to the positive diagnosis. “I was just on the phone with President Biden, and he shared his deep disappointment at not being able to join us this afternoon,” UnidosUS CEO Janet Murguía told attendees at the conference, according to CNN. “The president has been at many events as we all know, and he just tested positive for COVID.” JUST I…