If you want to do it yourself, there are metal epoxy putties out there. They come in a stick and you cut off what you need, then knead the two parts together. Use a wire wheel in a drill or Dremel tool to remove the paint around and on top of the rivet as well as rough up the aluminum. Press a small ball of the epoxy into the rivet and smooth it out with your fingers. If you wet your finger tips with a little water, you can blend the epoxy into a smooth repair.
As suggested by another, 5200 will work but is a lot more messy to deal with and takes a while to cure. It also requires moisture to fully cure and in dry, cold conditions that can take a while since there is little humidity in the air.