Generate Changelog

Sometimes, you have a changelog like this: (See frinyvonnick/gitmoji-changelog)

```{eval-sh}
cd ..
cat tests/changelog/CHANGELOG.md
```

This tool can generate a build/CHANGELOG.md.

```{eval-sh}
cd ..
cat tests/changelog/test/CHANGELOG.md
```

So you can

  - uses: softprops/action-gh-release@v1
    if: startsWith(github.ref, 'refs/tags/')
    with:
      body_path: build/CHANGELOG.md
      files: |
        dist
        sdist

More information can be seen in softprops/action-gh-release.