Bug 22038: Fix excel export if CurrencyFormat is FR

Bug 22038: Fix excel export if CurrencyFormat is FR

DataTables excel export is broken if number decimal separator is a comma.

Test plan:
1 - Set syspref CurrencyFormat to US
2 - Export as excel a table with decimal numbers, patrons list with fines
for example.
3 - Open in libreoffice or excel, numbers are ok.
4 - Set syspref CurrencyFormat to FR
5 - Export and open again, number are wrong 25,10 is imported as 2510
6 - Apply patch
7 - Redo 1 to 4
8 - Excel export, number is 25,10

Signed-off-by: hakam <hakam@inlibro.com>
Signed-off-by: Florian Bontemps <florian.bontemps@biblibre.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>