convert-ly doesn't catch `make-pango-font-tree`

[Werner LEMBERG]

[0cb681106e53c50d53a35304df639ad8a2a88cbc]


In my source file I have

```
\version "2.24"

\paper {
  fonts = #(make-pango-font-tree
            "Linux Libertine O"
            "Linux Biolinum O"
            "Ubuntu Mono"
            (/ (* staff-height pt) 2.5))
}
```

`convert-ly` of current git doesn't catch this.


    Werner