Update MPEG7 schema

[tledoux]

Hi,

the MPEG7 output refers in the xsi:schemaLocation attribute to an old schema : http://standards.iso.org/ittf/PubliclyAvailableStandards/MPEG-7_schema_files/mpeg7-v2.xsd
Since then, a new version has been released by ISO : http://standards.iso.org/ittf/PubliclyAvailableStandards/MPEG-7_schema_files/mpeg7-v4.xsd
All the associated schemas can be found at : http://standards.iso.org/ittf/PubliclyAvailableStandards/MPEG-7_schema_files

The new schema takes into account the different amendments/corrections of the standard but there is no changes in the part used by mediainfo (the description of the media) as well as no change to the associated namespace urn:mpeg:mpeg7:schema:2004.

The update will have no effect on the output and will point people to the latest version.
Thanks