Update to new wlr-randr home: https://sr.ht/~emersion/wlr-randr/

• d/control: Point to https://sr.ht/~emersion/wlr-randr/
• d/copyright: Point to https://git.sr.ht/~emersion/wlr-randr/
• d/watch: Update to watch https://git.sr.ht/~emersion/wlr-randr/

Also declare compliance with Policy 4.6.2.

After applying these changes, uscan will tell you there's a v0.3.0 release available upstream ;-)