Fixes the plugin header version. v1.3.0 was tagged before the header was bumped, so its ZIP reported 1.2.0 and would have re-offered itself as an update on every check.
Includes everything from v1.3.0:
- Reset stale "mode":"preview" attributes at parse time for blocks whose mode toggle is hidden, so no database clean-up is needed.
- Update from GitHub releases via the core Update URI mechanism, with a "Check for updates" link on the plugin row.