Cherry-picker

- Use `--no-tags` option when fetching upstream ([PR 319](https://github.com/python/core-workflow/pull/319))

- Modernize cherry_picker's pyproject.toml file ([PR 316](https://github.com/python/core-workflow/pull/316))

- Remove the `BACKPORT_COMPLETE` state. Unset the states when backport is completed
([PR 315](https://github.com/python/core-workflow/pull/315))

- Run Travis CI test on Windows ([PR 311](https://github.com/python/core-workflow/pull/311))

- Implement state machine and storing reference to the config
used at the beginning of the backport process using commit sha
and a repo-local Git config.
([PR 295](https://github.com/python/core-workflow/pull/295))

- Relaxed click dependency ([PR 302](https://github.com/python/core-workflow/pull/302))

- Validate the branch name to operate on with `--continue` and fail early if the branch could not
have been created by cherry_picker ([PR 266](https://github.com/python/core-workflow/pull/266))

- Bugfix: Allow `--continue` to support version branches that have dashes in them. This is
a bugfix of the additional branch versioning schemes introduced in 1.2.0.
([PR 265](https://github.com/python/core-workflow/pull/265)).

- Bugfix: Be explicit about the branch name on the remote to push the cherry pick to. This allows
cherry_picker to work correctly when the user has a git push strategy other than the default
configured ([PR 264](https://github.com/python/core-workflow/pull/264)).

- Add `default_branch` configuration item. The default is `master`, which
is the default branch for CPython. It can be configured to other branches like,
`devel`, or `develop`. The default branch is the branch cherry_picker
will return to after backporting ([PR 254](https://github.com/python/core-workflow/pull/254)
and [Issue 250](https://github.com/python/core-workflow/issues/250)).

- Support additional branch versioning schemes, such as `something-X.Y`,
or `X.Y-somethingelse`. ([PR 253](https://github.com/python/core-workflow/pull/253)
and [Issue 251](https://github.com/python/core-workflow/issues/251)).