Update .travis.yml

Author: ytake

.travis.yml

@@ -4,15 +4,18 @@ services:
 - docker
 env:
   matrix:
-    - HHVM_VERSION=4.35.0
-    - HHVM_VERSION=4.36.0
-    - HHVM_VERSION=4.38.0
-    - HHVM_VERSION=4.39.0
-    - HHVM_VERSION=4.40.0
     - HHVM_VERSION=4.41.0
     - HHVM_VERSION=4.42.0
     - HHVM_VERSION=4.43.0
     - HHVM_VERSION=4.44.0
+    - HHVM_VERSION=4.45.0
+    - HHVM_VERSION=4.46.0
+    - HHVM_VERSION=4.47.0
+    - HHVM_VERSION=4.48.0
+    - HHVM_VERSION=4.49.0
+    - HHVM_VERSION=4.50.0
+    - HHVM_VERSION=4.51.0
+    - HHVM_VERSION=4.52.1
     - HHVM_VERSION=latest
 install:
 - docker pull hhvm/hhvm-proxygen:$HHVM_VERSION