About window: clicking on "open source software" does nothing

[Junior Martins]

Steps to reproduce

1.Run /usr/lib/mozc/mozc_tool
2.Click on 'open source software'

Expected behavior

A window or webpage is opened.

Actual behavior

Nothing happens. The following message appears in the terminal:

```
gio: file:///usr/lib/mozc/documents/credits_en.html: Error when getting information for file “/usr/lib/mozc/documents/credits_en.html”: No such file or directory
```

System information:

OS: Ubuntu 23.04
Session type: Wayland
Mozc version: Mozc-2.28.4715.102+24.11.oss

Mozc packages found with `apt list --installed | grep mozc`:
```
ibus-mozc/lunar,now 2.28.4715.102+dfsg-2.2build1 amd64 [installed]
mozc-data/lunar,lunar,now 2.28.4715.102+dfsg-2.2build1 all [installed]
mozc-server/lunar,now 2.28.4715.102+dfsg-2.2build1 amd64 [installed]
mozc-utils-gui/lunar,now 2.28.4715.102+dfsg-2.2build1 amd64 [installed]
```

[Gunnar Hjalmarsson (gunnarhj)]

Thanks for your report! I pushed a fix to Debian's mozc repository:

https://salsa.debian.org/debian/mozc/-/commit/20c9819f

so this will be fixed next time mozc is uploaded.