linux-steam-integration: 0.7.2 -> 0.7.3

Release notes:
https://github.com/clearlinux/linux-steam-integration/releases/tag/v0.7.3

The same person (Ikey) who developed Linux Steam Integration have left
the Solus project where it was developed and works on Clearlinux now
instead, which seems to have picked up this project and made the first
release for a really long time.