fix: replace the asdf-micronaut plugin

[xafarr]

Summary

Description:

• Tool repo URL: Micronaut
• Plugin repo URL: https://github.com/xafarr/asdf-micronaut

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

[jthegedus]

Thanks