Remove Travis CI test for php 7.1 and 7.2

.travis.yml

@@ -16,8 +16,6 @@ branches:
   - hotfix
   - "/^(0|[1-9]\\d*)\\.(0|[1-9]\\d*)\\.(0|[1-9]\\d*)(-(0|[1-9]\\d*|\\d*[a-zA-Z-][0-9a-zA-Z-]*)(\\.(0|[1-9]\\d*|\\d*[a-zA-Z-][0-9a-zA-Z-]*))*)?(\\+[0-9a-zA-Z-]+(\\.[0-9a-zA-Z-]+)*)?$/"
 php:
-- 7.1
-- 7.2
 - 7.3
 env:
 - TRAVIS_NODE_VERSION="10"

composer.json

@@ -19,7 +19,7 @@
 	},
 	"config": {
 		"platform": {
-			"php": "7.1"
+			"php": "7.3"
 		}
 	},
 	"require": {