no sheets found in xlsx file

Hi, i have an excel .xlsx file which duckdb refuses to read until i re-saved it as xlsx with libreoffice (i dont have excel):
```
Binder Error:
No sheets found in xlsx file (is the file corrupt?)

LINE 1: select * from read_xlsx('./file.xlsx');
^
```

The only problem i can see with this file, is the following warning i get when loading it using python's pandas[excel] or directly openpyxl:
```
UserWarning: Workbook contains no default style, apply openpyxl's default
warn("Workbook contains no default style, apply openpyxl's default")

```

This sounds similar to #86, but i have no control over the creation of the file...

Start with the reported read_xlsx('./file.xlsx') entry point and compare the original workbook with the version re-saved by LibreOffice. Investigate why the original workbook's missing default style causes no sheets to be detected, using the openpyxl warning as a clue. Done means the original .xlsx file can be read successfully without re-saving it.

Written by the indexing model from the issue text.