List GPU price changes

FastGPU's price-change log: every list-price change its own record of posted prices confirms (a move between two prices that each held for two complete UTC days, at least a cent apart, on-demand and reserved, for providers that publish their own per-GPU rate) plus changes providers announce on their own pages, newest first. Each entry gives the provider, GPU, old and new price per GPU-hour, the change in percent, the day (or window) of the change and, for an announced change, the provider's page and wording. No key required.