Fewer Colorado homes are selling, and those that do are taking longer to move — a trend that could deepen as mortgage rates climb above 7%, adding to affordability concerns for would-be buyers. The average interest rate on a 30-year fixed mortgage rose to 7.09% on Friday, Sept. 18, climbing to its highest point in at least a year and a half, according to Bankrate. “It is definitely a psychological number for buyers and sellers, and people looki…