Remove unsupported versions of php and phpunit

Author: ajohnson6494

.travis.yml

@@ -1,11 +1,8 @@
 language: php
 
 php:
-  - 5.5
-  - 5.6
   - 7.0
   - 8.0
-  - hhvm
 
 # This triggers builds to run on the new TravisCI infrastructure.
 # See: http://docs.travis-ci.com/user/workers/container-based-infrastructure/
@@ -18,7 +15,7 @@ cache:
 
 matrix:
   include:
-    - php: 5.5
+    - php: 7.0
       env: 'COMPOSER_FLAGS="--prefer-stable --prefer-lowest"'
 
 before_script:

composer.json

@@ -19,10 +19,10 @@
         }
     ],
     "require": {
-        "php" : "~5.6 || ~7.0 || ~8.0"
+        "php" : "~7.0 || ~8.0"
     },
     "require-dev": {
-        "phpunit/phpunit" : "~4.0 || ~5.0 || ~6.0 || ~7.0 || ~8.0 || ~9.0",
+        "phpunit/phpunit" : "~8.0 || ~9.0",
         "scrutinizer/ocular": "~1.1",
         "squizlabs/php_codesniffer": "~2.3"
     },