Unit test against newer versions of MariaDB

- MariaDB 10.11 is readily installable on Rocky8 and is the version
  we run in production.
- MariaDB would appear to be the last version in the 10.X series.
- MariaDB 11.4 is the first version in the 11.X series, so test against it.
- Also test against the newest image in the 11.X series.
- Also test against the "latest" docker image available. In the near
  term, this is likely to the same image as "11". However testing
  against "latest" will mean we test against 12 automatically when
  it is released.
- Use `mariadb-admin` as admin command.
  - MariaDB <10.3 required mysqladmin be used.
  - MariaDB 10.4 to <11.0 allow both mysqladmin and mariadb-admin
    to be used.
  - MariaDB 11+ requires mariadb-admin.

.github/workflows/continuous-integration.yml

@@ -14,7 +14,7 @@ jobs:
         # Define jobs for all combinations of php, mariadb and extension, up to "include"
         # Tests will be performed for each combination
         php-version: ["7.4"]
-        mariadb-version: ["10.3"]
+        mariadb-version: ["10.11", "11.4", "11", "latest"]
         extension: ["pdo_mysql"]
         composer-json: ["composer.json"]
 
@@ -27,7 +27,7 @@ jobs:
           MYSQL_USER: "user"
           MYSQL_PASSWORD: "password"
 
-        options: --health-cmd="mysqladmin ping" --health-interval=5s --health-timeout=2s --health-retries=3
+        options: --health-cmd="mariadb-admin ping" --health-interval=5s --health-timeout=2s --health-retries=3
         ports:
           - "3306:3306"