Update python-schema to version 0.7.5 / rev 7 via SR 994424
https://build.opensuse.org/request/show/994424
by user StevenK + dimstar_suse
- Drop patch python-schema-no-mock.patch:
* Replaced by the below path.
- Add patch remove-old-python-support.patch:
* Remove support for old Python versions as well mock and contextlib2.
- Clean up {Build,}Requires as a result.