Fix: Drop HHVM from build matrix

Author: localheinz

.travis.yml

@@ -45,12 +45,6 @@ matrix:
     - php: 7.1
       env:
         - ZEND_SERVICEMANAGER_VERSION="^2.7.5"
-    - php: hhvm
-    - php: hhvm
-      env:
-        - ZEND_SERVICEMANAGER_VERSION="^2.7.5"
-  allow_failures:
-    - php: hhvm
 
 before_install:
   - if [[ $TEST_COVERAGE != 'true' ]]; then phpenv config-rm xdebug.ini || return 0 ; fi