remove duplicate php 7.0 and use php 7.1

Author: photodude

appveyor.yml

@@ -12,7 +12,7 @@ environment:
   - dependencies: highest
     php_ver_target: 7.0
   - dependencies: highest
-    php_ver_target: 7.0
+    php_ver_target: 7.1
 
 ## Cache composer bits
 cache:
@@ -47,4 +47,4 @@ install:
 ## Run the actual test
 test_script:
     - cd c:\projects\php-project-workspace
-    - vendor/bin/phpunit -c phpunit.xml.dist
+    - vendor/bin/phpunit -c phpunit.xml.dist