Update travis build matrix to supported php versions

.travis.yml

@@ -8,16 +8,12 @@ cache:
 
 matrix:
     include:
-        - php: 5.4
+        - php: 7.2
           env: check_cs=true
-        - php: 5.5
-        - php: 5.6
+        - php: 7.2
           env: deps=low coverage=true
-        - php: 5.6
-          env: deps=high coverage=true
-        - php: 7.0
-        - php: 7.1
         - php: 7.2
+          env: deps=high coverage=true
         - php: 7.3
 
 env:
@@ -39,7 +35,7 @@ script:
     - if [ "$coverage" = "true" ]; then vendor/bin/phpunit --coverage-clover=coverage; fi;
     - if [ "$coverage" = "true" ]; then xdebug-disable; fi;
     - if [ "$coverage" != "true" ]; then vendor/bin/phpunit; fi;
-    - if [ "$check_cs" = "true" ]; then vendor/bin/php-cs-fixer fix --config-file=.php_cs --dry-run --diff; fi;
+    - if [ "$check_cs" = "true" ]; then vendor/bin/php-cs-fixer fix --config=.php_cs --dry-run --diff; fi;
 
 after_script:
     - if [ "$coverage" = "true" ]; then wget https://scrutinizer-ci.com/ocular.phar; fi;