GHC 8.10.7

GHC 8.10.7 has been released! This release fixes a single bug that managed to slip into the recent GHC 8.10.6 release. I updated the docker-ghc image for easy testing. In doing so, I went ahead and renamed the tag to 8.10. The idea is to use a tag for each major branch, using the latest release for each branch, including previews, betas, release candidates, etc.