job specific docker images in gitlab ci

Author: Frederick888

.gitlab-ci.yml

@@ -6,6 +6,7 @@ before_script:
   - apt-get -y install autoconf build-essential gcc g++ valgrind
 
 php71:
+  image: php:7.1
   stage: build
   script:
     - phpize
@@ -19,6 +20,7 @@ php71:
       - modules/bencode.so
 
 php72:
+  image: php:7.2
   stage: build
   script:
     - phpize
@@ -32,6 +34,7 @@ php72:
       - modules/bencode.so
 
 php73:
+  image: php:7.3
   stage: build
   script:
     - phpize