Bump expected turbo version

Author: ondrejmirtes

src/Turbo/TurboExtensionEnabler.php

@@ -22,7 +22,7 @@ final class TurboExtensionEnabler
 	 * version is the short SHA of the last commit touching turbo-ext/src/,
 	 * enforced by the phar.yml turbo-version job.
 	 */
-	public const EXPECTED_EXTENSION_VERSION = 'f010107';
+	public const EXPECTED_EXTENSION_VERSION = '399c676';
 
 	private static bool $typeCombinatorCacheEnabled = false;