rss-email 0.4.0

The following changes require manual intervention:

* The `from` and `to` attributes in the configuration file have been
  moved to the `mail` section
* The sqlite database is now assumed to be in `$XDG_DATA_HOME/rss-email`
  by default (previously in `$XDG_CONFIG_HOME/rss-email`)

Hugo Osvaldo Barrera (3):
      Drop some unnecessary lettre features
      Leave a note on the impact of the "pool" feature
      Trace-log sending of individual messages

witcher (20):
      Update README.md with packages in AUR
      Allow urls to be commented out
      Supply defaults for optional command line args
      Be pedantic about E-Mail/email usage
      Update mailing list in man page
      Add man page for configuration files
      Fix format error for man page rss-email.1
      Add new man page to CI
      Extend README.md with new man page
      Introduce Mail struct
      Move `to` and `from` to `mail` section
      Extend Cargo.toml with more attributes
      Read clap command line info from Cargo.toml
      Don't create config folder by default
      Enable config file attributes on command line
      Replace env_logger with simple_logger
      Fix spelling of `sqlx-cli`
      Move `cache.db` to proper xdg dir
      Add `--no-fetch` to skip fetching feeds
      Specify RSS and Atom support in man page