It's Week 14 for the Medford Farmers Market at the Condon Band Shell Park, but due to Covid-19 restrictions, the live music again will be presented online. Performers will be Alex Cumming from 3 to 5 p.m., and Susan Cattaneo from 5 to 7 p.m.  Alex is a  singer, accordionist, pianist, tutor, dance caller, workshop leader and session musician. Susan is a folk singer who was a 2019 and 2018 Boston Music Awards nominee for Best Americana Artist. This week's…