chore(deps): update axllent/mailpit docker tag to v1.20.4

[renovate[bot]]

This PR contains the following updates:

Package	Update	Change	OpenSSF
axllent/mailpit (source)	patch	v1.20.2 -> v1.20.4

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Release Notes

axllent/mailpit (axllent/mailpit)

### [`v1.20.4`](https://redirect.github.com/axllent/mailpit/blob/HEAD/CHANGELOG.md#v1204) [Compare Source](https://redirect.github.com/axllent/mailpit/compare/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 ([#​357](https://redirect.github.com/axllent/mailpit/issues/357)) ### [`v1.20.3`](https://redirect.github.com/axllent/mailpit/blob/HEAD/CHANGELOG.md#v1203) [Compare Source](https://redirect.github.com/axllent/mailpit/compare/v1.20.2...v1.20.3) ##### Chore - Update caniemail database - Update node dependencies - Update Go dependencies - Do not recenter selected messages in sidebar on every new message ##### Fix - Disable automatic HTML/Text character detection when charset is provided ([#​348](https://redirect.github.com/axllent/mailpit/issues/348))

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Configuration

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