Remove hardcoded version from theme duplicate call

Now that the public theme duplicate mutation is
in in latest (rather than release candidate)
we no longer need to specify `2025-10` as the version

This commit removes the hardcoded version value
from the theme duplicate API call

Author: dejmedus

.changeset/fluffy-signs-peel.md

@@ -0,0 +1,5 @@
+---
+'@shopify/cli-kit': minor
+---
+
+Remove hardcoded theme duplicate mutation API version

packages/cli-kit/src/public/node/themes/api.test.ts

@@ -470,7 +470,6 @@ describe('themeDuplicate', () => {
         session,
         variables: {id: `gid://shopify/OnlineStoreTheme/${id}`, name},
         preferredBehaviour: expectedApiOptions,
-        version: '2025-10',
         responseOptions: {
           onResponse: expect.any(Function),
         },

packages/cli-kit/src/public/node/themes/api.ts

@@ -486,7 +486,6 @@ export async function themeDuplicate(
     session,
     variables: {id: composeThemeGid(id), name},
     preferredBehaviour: THEME_API_NETWORK_BEHAVIOUR,
-    version: '2025-10',
     responseOptions: {
       onResponse: (response) => {
         requestId = response.headers.get('x-request-id') ?? undefined