v6.4.0

What's Changed

• Use WP_Date instead by @LouGriffith in #8

All 13 date() calls replaced with wp_date() across 6 files:

shortcode-today.php — 4 calls (day name, today's date, and both header display lines)
shortcode-master.php — 2 calls (today + end date)
shortcode-schedule.php — 2 calls
shortcode-themed-rounds.php — 2 calls
shortcode-upcoming-themes.php — 2 calls
helpers.php — 3 calls (in cerrito_get_event_theme and cerrito_get_next_themed_date_for_day)

Full Changelog: v6.3.2...v6.4.0