fix(ui): visually distinguish the branch name in action description (#8418)

## Checklist

### Tests

I don't think this deserves a test.

### Documentation

- [ ] I created a pull request [to the documentation](https://codeberg.org/forgejo/docs) to explain to Forgejo users how to use this change.
- [x] I did not document these changes and I do not expect someone else to do it.

### Release notes

- [x] I do not want this change to show in the release notes.
- [ ] I want the title to show in the release notes with a link to this pull request.
- [ ] I want the content of the `release-notes/<pull request number>.md` to be be used for the release notes instead of the title.

### What does it fix

In the dashboard, when someone deletes a branch, the message
that is displayed doesn't distinguish the branch name from the rest
of the message visually. Because that's user-provided content, I find
it odd, as it blends in with the system-generated message.

For consistency with other messages (such as the one obtained when
renaming a repository), I propose to show the branch name in monospaced
font via the `<code></code>` markup.

I didn't update the other languages by fear of interfering with Weblate but
I would be happy to update the other languages accordingly if you wish so.

I didn't add any tests because I don't think it's necessary for such a small change.

#### Before
![image](/attachments/f158626e-fa58-4559-81b7-dd99045e1a33)
#### After
![image](/attachments/f12fe539-5c9a-4d13-a912-414591b8726d)
#### Renaming a repository (unchanged, just for reference)
![image](/attachments/a2366afb-6e24-4ad7-a41d-1c0ac6f04725)

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8418
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Reviewed-by: 0ko <0ko@noreply.codeberg.org>
Co-authored-by: Antonin Delpeuch <antonin@delpeuch.eu>
Co-committed-by: Antonin Delpeuch <antonin@delpeuch.eu>

options/locale/locale_ru-RU.ini

@@ -3639,7 +3639,7 @@ auto_merge_pull_request=`автоматически принят запрос н
 transfer_repo=репозиторий <code>%s</code> был передан: <a href="%s">%s</a>
 push_tag=отправлен тег <a href="%[2]s">%[3]s</a> в <a href="%[1]s">%[4]s</a>
 delete_tag=удалён тег %[2]s в <a href="%[1]s">%[3]s</a>
-delete_branch=удалена ветвь %[2]s в <a href="%[1]s">%[3]s</a>
+delete_branch=удалена ветвь <code>%[2]s</code> в <a href="%[1]s">%[3]s</a>
 compare_branch=Сравнить
 compare_commits=Сравнить %d коммитов
 compare_commits_general=Сравнить коммиты