try new workflow notation

Author: TamaroWalter

.github/workflows/config.json

@@ -2,12 +2,22 @@
   "main-moodle": "MOODLE_500_STABLE",
   "main-php": "8.3",
   "main-db": "pgsql",
-  "dbs": ["pgsql", "mariadb"],
-  "moodle-php": {
-    "MOODLE_401_STABLE": ["8.0", "8.1"],
-    "MOODLE_404_STABLE": ["8.1", "8.2", "8.3"],
-    "MOODLE_405_STABLE": ["8.1", "8.2", "8.3"],
-    "MOODLE_500_STABLE": ["8.2", "8.3", "8.4"]
+  "moodle-testmatrix": {
+    "MOODLE_401_STABLE": {
+      "php": ["8.0", "8.1"],
+    },
+    "MOODLE_404_STABLE": {
+      "php": ["8.1", "8.2", "8.3"],
+      "db": ["pgsql"]
+    },
+    "MOODLE_405_STABLE": {
+      "php": ["8.1", "8.2", "8.3"],
+      "db": ["pgsql", "mariadb", "mysqli"]
+    },
+    "MOODLE_500_STABLE": {
+      "php": ["8.2", "8.3", "8.4"],
+      "db": ["pgsql", "mariadb", "mysqli"]
+    }
   },
   "moodle-plugin-ci": "4.5.7"
-}
+}