ci: add winget install instructions & releaser workflow

[sitiom]

This action automatically generates manifests for Winget Community Repository (microsoft/winget-pkgs) and submits them.

I have just added duf the Winget (microsoft/winget-pkgs#97752), and this workflow should keep it up to date.

Before merging this:

1. Add a classic PAT with public_repo scope as a repository secret named WINGET_TOKEN. You can go to this URL to create it: https://github.com/settings/tokens/new?scopes=public_repo

2. Fork https://github.com/microsoft/winget-pkgs under @muesli. The action will use that fork for making a branch and creating a PR with the upstream winget-pkgs repository on every release.
3. Install Pull on the winget-pkgs fork to ensure that it is constantly updated.

If you want to see an example of a PR created using this action, see microsoft/winget-pkgs/pulls (Pull request has been created with WinGet Releaser).

[sitiom]

@muesli Bump

[muesli]

I'll check it out! I've just never used winget before, so may need to get familiar with it first.