[HttpKernel] Use Accept-Language header even if there are no enabled locales

Author: MatTheCat

CHANGELOG.md

@@ -18,7 +18,8 @@ CHANGELOG
    `workflow.state_machine`
  * Add `rate_limiter` configuration option to `messenger.transport` to allow rate limited transports using the RateLimiter component
  * Remove `@internal` tag from secret vaults to allow them to be used directly outside the framework bundle and custom vaults to be added
- * Deprecate "framework.form.legacy_error_messages" config node
+ * Deprecate `framework.form.legacy_error_messages` config node
+ * Set locale from request rather than default locale if `framework.enabled_locales` is empty and `framework.set_locale_from_accept_language` is true
 
 6.1
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