Add DB matrix

Author: schlessera

.github/workflows/testing.yml

@@ -64,25 +64,46 @@ jobs:
       matrix:
         php: ['5.6', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0']
         wp: ['latest']
+        mysql: ['8.0']
         test: ["composer behat || composer behat-rerun"]
         include:
           - php: '5.6'
             wp: 'trunk'
+            mysql: '8.0'
+            test: "composer behat || composer behat-rerun"
+          - php: '5.6'
+            wp: 'trunk'
+            mysql: '5.7'
+            test: "composer behat || composer behat-rerun"
+          - php: '5.6'
+            wp: 'trunk'
+            mysql: '5.6'
             test: "composer behat || composer behat-rerun"
           - php: '7.4'
             wp: 'trunk'
+            mysql: '8.0'
+            test: "composer behat || composer behat-rerun"
+          - php: '8.0'
+            wp: 'trunk'
+            mysql: '8.0'
+            test: "composer behat || composer behat-rerun"
+          - php: '8.0'
+            wp: 'trunk'
+            mysql: '5.7'
             test: "composer behat || composer behat-rerun"
           - php: '8.0'
             wp: 'trunk'
+            mysql: '5.6'
             test: "composer behat || composer behat-rerun"
           - php: '5.6'
             wp: '3.7'
+            mysql: '5.6'
             test: "composer behat || composer behat-rerun"
     runs-on: ubuntu-latest
 
     services:
       mysql:
-        image: mysql:5.7
+        image: mysql:${{ matrix.mysql }}
         env:
           MYSQL_DATABASE: wp_cli_test
           MYSQL_USER: root