Remove php 7.1 for coverage

Author: joelwurtz

.travis.yml

@@ -23,7 +23,7 @@ branches:
 matrix:
     fast_finish: true
     include:
-        - php: 7.1
+        - php: 7.2
           env: COMPOSER_FLAGS="--prefer-stable --prefer-lowest" COVERAGE=true TEST_COMMAND="composer test-ci"
         - php: 7.2
           env: COMPOSER_FLAGS="--prefer-stable --prefer-lowest"