1.0.0 release

This package has existed for a while, but I've just done a bunch of work to bring it up to date with Julia 1.6+. Here are some of the new improvements:

• Handle Manifest.toml version 2.0
• Improved reproducibility and better ease-of-use via flakes (now you can run it straight from GitHub without cloning!)
• We have CI now, currently testing Julia 1.6 and 1.8
• Improved Artifacts.toml handling (fixing a bug where only 1 artifact matching the given os/arch was included)

I'm tagging this stuff as version 1.0.0.

Coming soon: support for select_artifacts.jl.