fix(deps): update dependency amphp/parallel to v2

Author: renovate[bot]

composer.json

@@ -4,7 +4,7 @@
 	"type": "library",
 	"require": {
 		"amphp/amp": "^2.6.5",
-		"amphp/parallel": "^1.4.4",
+		"amphp/parallel": "^2.4.0",
 		"bamarni/composer-bin-plugin": "^1.9.1",
 		"rubix/ml": "^2.5.3",
 		"wamania/php-stemmer": "4.0 as 3.0"