Changelog automation

[n-dusan]

After #34 , we can autogenerate changelog with git-cliff

[tombh]

We use git-cliff in Pygls:
Here's the config https://github.com/openlawlibrary/pygls/blob/main/cliff.toml and this is how we run it during release https://github.com/openlawlibrary/pygls/blob/main/.github/workflows/release.yml#L23