chore: remove deprecated flag (#3334)

Author: LynxLynxx

catalyst_voices/packages/internal/catalyst_voices_localization/l10n.yaml

@@ -6,6 +6,5 @@ output-class: VoicesLocalizations
 preferred-supported-locales:
   - en
 use-deferred-loading: true
-synthetic-package: false
 use-escaping: false
 relax-syntax: true