Police have not kept up with the risks posed to the public by social media, a review of the response to last summer's UK riots has found. Mosques and hotels housing migrants were among the targets of violence which erupted after Axel Rudakubana stabbed three girls to death at a Taylor Swift-themed dance class in Southport in July. The police inspectorate found no conclusive evidence the disorder was co-ordinated by extremist groups but said it was mostly incited by "disaffected individuals, influencers or groups" online. A report published on Wednesday said most of those involved were local and the violence…