LONDON -- British singer Rita Ora apologized Monday for breaking lockdown rules by holding a birthday party, saying it was “a serious and inexcusable error of judgment.”The Sun newspaper ran photos of Ora and others, including models Cara and Poppy Delevingne, arriving at the Casa Cruz restaurant in London’s Notting Hill area on Saturday.Under lockdown rules that end Wednesday, all pubs and restaurants in England must close except for takeout and delivery, and people are barred from meeting