events: add v1.6.8-aio.3

Honours per-wave fiat when the organiser set an explicit payment-method
list (aiolabs/events#67). The published tickets_payment_methods tag no
longer advertises fiat for a wave that cannot take it, which previously
contradicted the same event's absent tickets_allow_fiat and produced a
card button the purchase endpoint refused.

Eight lines in models.py; no schema change, no migration. Added
alongside v1.6.8-aio.2 rather than over it. Archive sha256 verified
against two independent fetches and spot-checked for the fix.

extensions.json

@@ -375,6 +375,16 @@
             "archive": "https://git.atitlan.io/aiolabs/events/archive/v1.6.8-aio.2.zip",
             "hash": "e6ece033103b716790f1c6a01c58aac281518e102ce5fe9bfd782102ec165f3d"
         },
+        {
+            "id": "events",
+            "repo": "https://git.atitlan.io/aiolabs/events",
+            "name": "AIO Events",
+            "version": "1.6.8-aio.3",
+            "short_description": "A ticket wave that does not accept card is no longer advertised as if it did. The organiser's payment-method list is event-level while fiat is a per-wave opt-in, so the published tags and the checkout could offer a card button the purchase endpoint then refused.",
+            "icon": "https://git.atitlan.io/aiolabs/events/raw/branch/main/static/image/events.png",
+            "archive": "https://git.atitlan.io/aiolabs/events/archive/v1.6.8-aio.3.zip",
+            "hash": "c626273785537caf13b0233e0f682586b710c363071c6fe8cb3c5163542dd492"
+        },
         {
             "id": "nostrclient",
             "repo": "https://git.atitlan.io/aiolabs/nostrclient",