Git-machete

- fixed: readability of autogenerated PR/MR descriptions
- improved: `git machete github restack-pr` and `git machete gitlab restack-mr` fail on branches marked as `push=no`, instead of printing a warning and proceeding with retargeting anyway

- added: better detection of squash merges and rebases, controlled by flag `--squash-merge-detection={none,simple,exact}` (`status` and `traverse`) and git config key `machete.squashMergeDetection` (contributed by gjulianm)
- deprecated: `--no-detect-squash-merges` flag in `status` and `traverse` — use `--squash-merge-detection=none` instead (contributed by gjulianm)

- fixed: `-y` option in `git machete traverse` automatically sets `--no-edit-merge` flag, to retain behavior when the `update=merge` qualifier is set (contributed by gjulianm)
- fixed: `push=no` and `slide-out=no` qualifiers now work in `git machete advance` now
- fixed: `rebase=no` qualifier now works in `git machete slide-out`
- improved: in `git machete github create-pr`/`gitlab create-mr`, check whether base/target branch for PR/MR exists in remote, instead of fetching the entire remote

- fixed: Homebrew deploys

- fixed: `git machete git{hub,lab} restack-{pr,mr}` now first retargets, then pushes (so that certain CIs see the correct base branch in env vars)

- added: GitLab support via `git machete gitlab` (first suggested by mikeynap, partly contributed by max-nicholson)
- added: `git machete anno -L`/`--sync-gitlab-mrs` flag
- fixed: checking out GitHub PRs where head branch comes from an already deleted fork
- added: qualifier `update=merge` allows selecting merge strategy per branch (contributed by gjulianm)
- added: Scoop package for Windows (suggested by ppasieka)