Add 8.1 image

Author: matthiasmullie

docker-compose.yml

@@ -9,6 +9,11 @@ services:
       - ./data:/var/www/data
       - ./tests:/var/www/tests
       - ./phpunit.xml.dist:/var/www/phpunit.xml.dist
+  '8.1':
+    extends: php
+    build:
+      args:
+        version: 8.1-cli
   '8.0':
     extends: php
     build:

makefile

@@ -1,4 +1,4 @@
-PHP ?= '7.2'
+PHP ?= '8.1'
 UP ?= 1
 DOWN ?= 1