bump hhvm version

Author: azjezz

.travis.yml

@@ -5,8 +5,7 @@ os:
   - linux
 
 env:
-  - HHVM_VERSION=4.25-latest
-  - HHVM_VERSION=4.30-latest
+  - HHVM_VERSION=4.56-latest
   - HHVM_VERSION=latest
   - HHVM_VERSION=nightly
 

composer.json

@@ -14,9 +14,9 @@
         }
     ],
     "require": {
-        "hhvm": "^4.25",
-        "hhvm/hsl": "^4.25",
-        "hhvm/hsl-experimental": "^4.50"
+        "hhvm": "^4.56",
+        "hhvm/hsl": "^4.40",
+        "hhvm/hsl-experimental": "^4.40"
     },
     "require-dev": {
         "facebook/fbexpect": "^2.7",