Temporarily prevent installing reactphp/http >=1.3

There seems to be a problem with the newest react keepalive feature, avoiding that release until further investigations are conducted see php-pm#538

Author: acasademont

composer.json

@@ -9,7 +9,7 @@
         "symfony/error-handler": "^4.4|^5",
         "symfony/process": "^3.4|^4|^5",
         "react/event-loop": "^1.0",
-        "react/http": "^1.0",
+        "react/http": ">=1.0 <1.3",
         "react/stream": "^1.0",
         "react/socket": "^1.0",
         "react/child-process": "^0.6",