Add rdbms matrix for wider compatibility testing

This change set introduces a `rdbms` matrix with the purpose of increasing insurance this package works with up to the latest MySQL/MariaDB versions.

Note that due to MySQL's versioning there are no `v6` and `v7`.

Refs: friends-of-reactphp#194

.github/workflows/ci.yml

@@ -6,10 +6,12 @@ on:
 
 jobs:
   PHPUnit:
-    name: PHPUnit (PHP ${{ matrix.php }})
+    name: PHPUnit (PHP ${{ matrix.php }}; RDBMS ${{ matrix.rdbms }})
     runs-on: ubuntu-22.04
     strategy:
       matrix:
+        rdbms:
+          - mysql:5
         php:
           - 8.3
           - 8.2
@@ -23,6 +25,9 @@ jobs:
           - 5.6
           - 5.5
           - 5.4
+        include:
+          - php: 8.3
+            rdbms: mariadb:10
     steps:
       - uses: actions/checkout@v4
       - uses: shivammathur/setup-php@v2
@@ -31,7 +36,7 @@ jobs:
           coverage: xdebug
           ini-file: development
       - run: composer install
-      - run: docker run -d --name mysql --net=host -e MYSQL_RANDOM_ROOT_PASSWORD=yes -e MYSQL_DATABASE=test -e MYSQL_USER=test -e MYSQL_PASSWORD=test mysql:5
+      - run: docker run -d --name mysql --net=host -e MYSQL_RANDOM_ROOT_PASSWORD=yes -e MYSQL_DATABASE=test -e MYSQL_USER=test -e MYSQL_PASSWORD=test ${{ matrix.rdbms }}
       - run: bash tests/wait-for-mysql.sh
       - run: vendor/bin/phpunit --coverage-text
         if: ${{ matrix.php >= 7.3 }}