fix: migrate purescript and spago to a new username

[jrrom]

Summary

Description:

• Tool repo URL: purescript, spago
• Plugin repo URL: purescript, spago

Checklist

• Format with scripts/format.bash
• Test locally with scripts/test_plugin.bash --file plugins/<your_new_plugin_name>
• Your plugin CI tests are green
  • Tip: use the plugin_test action from asdf-actions in your plugin CI

[jrrom]

The previous maintainer of asdf-purescript and asdf-spago is archived, so I would like to take up maintaining duties.

[jthegedus]

Thanks