Release v1.3.0-rc.0

Bug Fixes
- Fix previous release references (fbb605e)

Documentation
- Add example for generating changelog similar to cocogitto (e1cf26e)
- Update the header of configuration examples (0bf5ebe)

Features
- (breaking) Add postprocessors (#155) (5dc5fb7)

Miscellaneous Tasks
- Make git2 optional (5fdf39a)
- Check without default features (e323621)
- Add config for welcome bot (a4725d4)
- Skip dependency updates in the changelog (b2edc23)
- Add configuration file for automatic merge (#245) (0a79aae)
- Rename mergify configuration file (9fd1be6)
- Publish `git-cliff` on PyPI (#158) (2b7a1ef)
- Update configuration for alpha/beta/rc releases (7e7e5a7)
- Support creating prereleases on GitHub (a22426a)
- Add additional parsers for default config (b745778)

Refactor
- Avoid copying volume inside container (#142) (65d365c)
- Apply clippy suggestions (a814bbe)
- Apply clippy suggestions (4c09759)
- Use implicit serde imports (c8cf855)

Styling
- Fix formatting (14725e5)
- Apply formatting to configuration files (e9aa991)
- Further beautify the changelog in this repo (fd7446c)

Testing
- Add an informative error message to failing test (7d7470b)
- Add cases for `docs:` prefix (#167) (3a717e2)
- Fix keep a changelog test case (f5d3365)
- Fix keep a changelog test case (0a6ed62)