Hopefully this makes releases a little better for users.
In particular, this avoids listing old build artifacts in the SHA256SUMS
files when we make new releases, and users can now download them
directly.
Now to make a release you run: `make tag && make release`.
After the first make session ends, you'll have a new tag released
publicly, and then during the second make session, the release target
will notice this new tag, build some assets, and upload them!
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