Follow wp-countries on dev-main, as every sibling is followed

The regions the region type needs are on main and not in a tag, and
no library here pins another to a tag.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015Kwx2STJ4EaVaJofEJJ9Zo

Author: arraypress

composer.json

@@ -12,7 +12,7 @@
   ],
   "require": {
     "php": ">=8.3",
-    "arraypress/wp-countries": "^1.0"
+    "arraypress/wp-countries": "dev-main"
   },
   "require-dev": {
     "phpcompatibility/phpcompatibility-wp": "^2.1",