Update odf.php

I don't know why but this difference betwenn the old versionand the new one in Dolibarr make crash "Error during file export addFromString" the doc_generic_project_odt.modules.php. I compare the new version and the older and this is the only thing I found. If I remove this require_one it works fine
Merge pull request #2 from FHenry/patch-1

fix: Useless requires removed in odf.php