Remove date_precision for Ruby for Good - Belgium 2026

Author: marcoroth

_data/conferences.yml

@@ -3234,7 +3234,6 @@
   location: Ghent, Belgium
   start_date: 2026-02-02
   end_date: 2026-02-04
-  date_precision: month
   url: https://rubyinghent.org
   announced_on: 2025-10-01