Remove EOL PHP versions (5.6 and 7.0)

Author: tianon

.travis.yml

@@ -2,14 +2,6 @@ language: bash
 services: docker
 
 env:
-  - VARIANT=php5.6/apache
-  - VARIANT=php5.6/fpm
-  - VARIANT=php5.6/fpm-alpine
-  - VARIANT=php5.6/cli
-  - VARIANT=php7.0/apache
-  - VARIANT=php7.0/fpm
-  - VARIANT=php7.0/fpm-alpine
-  - VARIANT=php7.0/cli
   - VARIANT=php7.1/apache
   - VARIANT=php7.1/fpm
   - VARIANT=php7.1/fpm-alpine