build(deps): update axllent/mailpit to v1.20.4

This MR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [axllent/mailpit](https://github.com/axllent/mailpit) | patch | `v1.20.3` -> `v1.20.4` |

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.**

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### Release Notes

<details>
<summary>axllent/mailpit (axllent/mailpit)</summary>

### [`v1.20.4`](https://github.com/axllent/mailpit/blob/HEAD/CHANGELOG.md#v1204)

[Compare Source](axllent/mailpit@v1.20.3...v1.20.4)

##### Chore

-   Update Go modules
-   Update node modules
-   Upgrade vue-css-donut-chart & related charts

##### Fix

-   Relax URL detection in link check tool ([#&#8203;357](axllent/mailpit#357))

</details>

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### Configuration

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chezmoi/dot_config/aquaproj-aqua/aqua.yaml

@@ -277,7 +277,7 @@ packages:
 - name: yassinebridi/[email protected]
   description: A simple terminal UI for search and replace, ala VS Code
   link: https://github.com/yassinebridi/serpl
-- name: axllent/[email protected].3
+- name: axllent/[email protected].4
   description: An email and SMTP testing tool with API for developers
   link: https://github.com/axllent/mailpit
 - name: mrjackwills/[email protected]