fix: add uv sync step to SDK version determination job (#12695)

The determine-sdk-version job was missing the 'uv sync' step that creates
the cache, causing the 'Post Setup Environment' step to fail with:
'cache path does not exist on disk'

This matches the pattern used in determine-lfx-version job (line 247) and
the nightly build workflow (line 104-105).

Fixes the SDK build failure in release workflow dry run.