net-p2p/deluge: update to 2.0.3

2.0 release notes: https://deluge.readthedocs.io/en/latest/releases/2.0.html
2.0.3 changelog: https://deluge.readthedocs.io/en/latest/changelog.html

This update includes migrating to python3/gtk3 stack and some extra stability
fixes from upstream repository, not yet released.

The port still need rc-scripts to be adjusted to run in headless mode out of
the box, but user may just toggle "Auto-connect to selected daemon" and
"Auto-start localhost daemon" or click "Start daemon" button in connection
manager window to make things happen. This (rc-scripts update) would be done
later when time permits.

PR: 241202
Reported by: many