remove mariadb 11.x and 12.x from build matrix

reason: github actions fail to start them with error:

"mariadbd: io_uring_queue_init() failed with EPERM: sysctl kernel.io_uring_disabled has the value 2,
or 1 and the user of the process is not a member of sysctl kernel.io_uring_group. (see man 2 io_uring_setup)."

the internet wisdom says to disable io_uring for mariadb, because github ubuntu runners disable it at kernel level.
i could not find a way to pass "skip-innodb-use-native-aio" to mariadb using github actions.

Author: goekay

.github/workflows/main.yml

@@ -8,7 +8,7 @@ jobs:
       matrix:
         os: [ ubuntu-latest ]
         java: [ '21', '23', '25' ]
-        db: [ 'mysql:8.0', 'mysql:8.4', 'mariadb:10.6.14', 'mariadb:11.8.5', 'mariadb:12.1.2']
+        db: [ 'mysql:8.0', 'mysql:8.4', 'mariadb:10.6.14']
     runs-on: ${{ matrix.os }}
     services:
       mysql: