chore: upgrade openspout to 5.x

openspout/openspout 4.32.0 → 5.7.0. PowerGrid v6.10.x ships a v5 export adapter
out of the box — config swapped from openspout_v4 to openspout_v5. v3 adapter
references removed (no longer shipped by PowerGrid).

Test suite: 207 passing, 10 preexisting failures unchanged.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

composer.json

@@ -20,7 +20,7 @@
         "livewire/flux-pro": "^2.10",
         "livewire/livewire": "^4.0",
         "livewire/volt": "^1.0",
-        "openspout/openspout": "^4.24",
+        "openspout/openspout": "^5.0",
         "power-components/livewire-powergrid": "^6.7",
         "pusher/pusher-php-server": "^7.2.2",
         "ralphjsmit/laravel-seo": "^1.7",