luacheckrc: Replace deprecated module:once with :on_ready
So that :once is warned about properly.
module:once was only added in trunk so it shouldn't have gotten very far
yet.
--- a/.luacheckrc Sat Dec 02 11:07:23 2023 +0100
+++ b/.luacheckrc Sat Dec 02 11:10:43 2023 +0100
@@ -62,7 +62,7 @@
"module.may",
"module.measure",
"module.metric",
- "module.once",
+ "module.on_ready",
"module.open_store",
"module.provides",
"module.remove_item",