CI: Add automatic nightly build to the workflow

[sxyazi]

Please describe the problem you're trying to solve

This will allow users to download pre-built binaries from the release page instead of building them themselves.

It will also benefit downstream projects like yazi.nvim, where automated testing in CI relies on the latest nightly version for some features, mikavilpas/yazi.nvim#135 (comment).

Would you be willing to contribute this feature?

• Yes, I'll give it a shot

Describe the solution you'd like

Add a workflow for nightly builds to the current GitHub Actions

Additional context

No response

[uznog]

I'll open a PR soon!

[sxyazi]

Done in #1397, thanks for contributing this feature @uznog!

[github-actions]

I'm going to lock this issue because it has been closed for 30 days. ⏳
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