bug: flyctl packaging filename change

[chessmango]

Describe the bug

Between https://github.com/superfly/flyctl/releases/tag/v0.0.513 and https://github.com/superfly/flyctl/releases/tag/v0.0.517, underscore dropped after platform name. Unclear why, as code changes don't imply this necessarily
Steps to reproduce

Expected behavior

Release filenames should be the same, probably. Though not a given
Screenshots

Additional context

[chessmango]

Raised issue in PR: superfly/flyctl#2074

[dangra]

skip that version and bump to https://github.com/superfly/flyctl/releases/tag/v0.0.518

[chessmango]

Thanks @dangra! ❤️