Addon - Squash Git commits - Template markup not working

### Describe the issue

I see template markup (variables) in commit message instead of strings these variables represent.

[Documentation of addon-weblate-git-squash](https://docs.weblate.org/en/latest/admin/addons.html#addon-weblate-git-squash)) indicates it should work:

> The original commit messages can optionally be overridden with a custom commit message. See [Template markup](https://docs.weblate.org/en/latest/admin/projects.html#markup) for the message options.

### I already tried

- [X] I've read and searched [the documentation](https://docs.weblate.org/).
- [X] I've searched for similar issues in this repository.

### Steps to reproduce the behavior

1. Go to component addons. Add addon "Squash Git commits".
2. Configure it as follows:
- Commit squashing - per file
- Append trailers to squashed commit message - checked
- Commit message - use template markup. Eg. `Translated using Weblate ({{ language_name }} / {{ filename }})`
3. Check commits. You'll see template markup instead of strings it should generate.

### Expected behavior

Template markup should be processed and it should generate strings in place of variables.

### Screenshots

Addon configuration:

Repository maintenance page:

GitLab MR:

### Exception traceback

_No response_

### How do you run Weblate?

weblate.org service

### Weblate versions

_No response_

### Weblate deploy checks

_No response_

### Additional context

_No response_