Bump shared-mime-info to 1.3

Bump the build time requirement, and assumed runtime, version of
shared-mime-info to 1.3, which seems to be a good low-enough baseline
according to:
https://repology.org/metapackage/shared-mime-info/versions

This makes it possible to drop a number of definitions provided by
newer versions of shared-mime-info:

• all the Microsoft OOXML mime types
• application/x-iwork-keynote-sffkey