Remove test support for EOL PHP Versions (5.3, 5.4, 5.5, 5.6, 7.0), Add support for 7.2, 7.3.

Author: jbwyme

.travis.yml

@@ -3,17 +3,9 @@ sudo: false
 dist: trusty
 
 php:
-  - 5.4
-  - 5.5
-  - 5.6
-  - 7.0
   - 7.1
-
-matrix:
-  include:
-    - php: 5.3
-      dist: precise
-      sudo: true
+  - 7.2
+  - 7.3
 
 install:
   - travis_retry composer self-update