chore(changeset): add patch updates for @vue3-apollo/core and @vue3-apollo/nuxt

Author: guendev

.changeset/clean-roses-kiss.md

@@ -0,0 +1,8 @@
+---
+"@vue3-apollo/core": patch
+"@vue3-apollo/nuxt": patch
+---
+
+fix(core): improve reactive variable handling in `useQuery` and `useSubscription`
+- Replaced `syncRef` with `computed` for `reactiveVariables`.
+- Simplified variable updates to improve reactivity and reduce overhead.