Cosmetic changes

- Add a spinner to posts retrieval
- Improve loading indicators
- Add Top authors

Add support for CLI arguments

Filter on time range
--since=<duration> (e.g. 1h, 30m, 5d, 2w, 30d, 1y)

Limit results to last X messages
--limit=<number>

--limit=0 to disable the limit

Filter on one author
--author=<login>

Add gh-extension release via GitHub Actions

The binary is now built and released via the GitHub Actions workflow.

This will prevent user to build the binary manually.

This also removes the need for users to have Go installed on their
machines.

Improve rendering

First installer

First version