Bump dependencies.

Author: richardhj

composer.json

@@ -21,10 +21,10 @@
     "guzzlehttp/guzzle": "^6.0",
     "isotope/isotope-core": "^2.4",
     "klarna/kco_rest": "^3.0",
-    "symfony/dependency-injection": "^3.3",
-    "symfony/http-foundation": "^3.3",
-    "symfony/http-kernel": "^3.3",
-    "symfony/routing": "^3.3"
+    "symfony/dependency-injection": "^3.3 || ^4.0",
+    "symfony/http-foundation": "^3.3 || ^4.0",
+    "symfony/http-kernel": "^3.3 || ^4.0",
+    "symfony/routing": "^3.3 || ^4.0"
   },
   "autoload": {
     "psr-4": {