[Theme request] Add hexo theme diaspora

We accept themes that meet the following criteria.

- Under the MIT license.
- Have a public Git repository URL.

Go over all the following points, and put an `x` in all the boxes that apply.

- [x] You Like it
- [ ] You Forked it
- [ ] You Created it

**Theme Link**:

[hexo-theme-diaspora](https://github.com/Fechin/hexo-theme-diaspora)

**Additional context**: Add any other context about the theme here.

The issue provides no file, test, or entry point; begin by locating how this repository adds or lists themes, then inspect the linked hexo-theme-diaspora repository. Done means the theme is added while meeting the stated MIT-license and public-repository criteria.

Written by the indexing model from the issue text.