Gh-reader

What's Changed
* feat: support fsspec and since parameter by machow in https://github.com/machow/gh_reader/pull/2


**Full Changelog**: https://github.com/machow/gh_reader/compare/v0.0.2...v0.0.3

Each record of issue_events cleaned, now has the form:


{ issue_id: ..., type: "SomeEvent", data: { ... } }


Prior to this, the fields in data were flattened. The new form makes clear where the unstructured data all lives.