COLUMBIA, Mo. (KMIZ) People around Columbia celebrated Juneteenth on Friday. Juneteenth is a federal holiday that commemorates the end of slavery in the United States. Volunteers helped Powerhouse Community Development put on its third annual event on Friday at Cosmo Park. A community luncheon and another event were held at Douglass Park the same day. Information from the city shows several events are also scheduled for Saturday, including a par…