build(deps): update git-town/git-town to v21.3.0

This MR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [git-town/git-town](https://github.com/git-town/git-town) | minor | `v21.2.0` -> `v21.3.0` |

MR created with the help of [el-capitano/tools/renovate-bot](https://gitlab.com/el-capitano/tools/renovate-bot).

**Proposed changes to behavior should be submitted there as MRs.**

---

### Release Notes

<details>
<summary>git-town/git-town (git-town/git-town)</summary>

### [`v21.3.0`](https://github.com/git-town/git-town/releases/tag/v21.3.0)

[Compare Source](git-town/git-town@v21.2.0...v21.3.0)

##### New Features

*[setup assistant](https://www.git-town.com/commands/config-setup.html):*

- now creates configuration files with name `git-town.toml` instead of the deprecated `git-branches.toml` ([#&#8203;5162](git-town/git-town#5162))
- now gives the user a chance to enter the [observed regex](https://www.git-town.com/preferences/observed-regex.html) and [contribution regex](https://www.git-town.com/preferences/contribution-regex.html), ([#&#8203;5133](git-town/git-town#5133), [#&#8203;5132](git-town/git-town#5132))
- when entering perennial branches, the main and perennial branches from the config file are now preselected and locked ([#&#8203;5154](git-town/git-town#5154))
- no longer asks for the [dev remote](https://www.git-town.com/preferences/dev-remote.html) if only one Git remote exists ([#&#8203;5153](git-town/git-town#5153))
- now updates Git metadata only if the user entered a different value than already exists ([#&#8203;5127](git-town/git-town#5127))
- no longer creates commented out entries ([#&#8203;5110](git-town/git-town#5110))
- now explains how to run it manually ([#&#8203;5155](https://github.com/git-town/git-town/pull/5155/files))

##### Bug Fixes

- updating the base branch in a stack using the [gh connector](https://www.git-town.com/preferences/github-connector.html) works now ([#&#8203;5163](git-town/git-town#5163))
- setup assistant:
  - now displays the entered value for the API token scope ([#&#8203;5144](git-town/git-town#5144))
  - more consistent dialog captions ([#&#8203;5159](git-town/git-town#5159))

##### Contributors

Shoutout to [@&#8203;kevgo](https://github.com/kevgo), [@&#8203;stephenwade](https://github.com/stephenwade), [@&#8203;wengh](https://github.com/wengh) for contributing code, ideas, and feedback to 52 shipped MRs and 1 resolved issue!

</details>

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

♻ **Rebasing**: Whenever MR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 **Ignore**: Close this MR and you won't be reminded about this update again.

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this MR, check this box

---

This MR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).
<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiI0MC42Mi4xIiwidXBkYXRlZEluVmVyIjoiNDAuNjIuMSIsInRhcmdldEJyYW5jaCI6Im1haW4iLCJsYWJlbHMiOlsiUmVub3ZhdGUgQm90Il19-->

Author: ECG Bot

chezmoi/dot_config/aquaproj-aqua/aqua.yaml

@@ -59,7 +59,7 @@ packages:
 - name: getsops/[email protected]
   description: Simple and flexible tool for managing secrets
   link: https://github.com/getsops/sops
-- name: git-town/git-town@v21.2.0
+- name: git-town/git-town@v21.3.0
   description: Git workflow automation to keep branches in sync and reduce merge conflicts
   link: https://github.com/git-town/git-town
 - name: mr-karan/[email protected]