Downgrade dependencies to pass on CI

Author: ace-n

appengine/flexible/websockets/composer.json

@@ -2,10 +2,10 @@
     "require": {
         "cboden/ratchet": "^0.4.1",
         "guzzlehttp/psr7": "^1.5",
-        "silex/silex": "^2.3"
+        "silex/silex": "^1.3"
     },
     "require-dev": {
-    	"phpunit/phpunit": "^7.5",
+    	"phpunit/phpunit": "^5",
     	"ratchet/pawl": "^0.3.4",
         "react/promise": "^2.7",
         "clue/block-react": "^1.3",