Bump quarkus version from 3.11 to 3.12

[cmoulliard]

Issue

We should bump the quarkus version from 3.11 to 3.12 as code.quarkus.io uses a default now: 3.12. Without doing that scaffolding will fail using 3.11 within the e2e

{
    "id": 3,
    "taskId": "06919063-267b-474f-9d28-c527b6101e3a",
    "body": {
      "message": "AxiosError: Request failed with status code 400\n    at settle (/home/runner/work/backstage-playground/backstage-playground/node_modules/axios/lib/core/settle.js:19:12)\n    at IncomingMessage.handleStreamEnd (/home/runner/work/backstage-playground/backstage-playground/node_modules/axios/lib/adapters/http.js:589:11)\n    at IncomingMessage.emit (node:events:531:35)\n    at endReadableNT (node:internal/streams/readable:1696:12)\n    at process.processTicksAndRejections (node:internal/process/task_queues:82:21)\n    at Axios.request (/home/runner/work/backstage-playground/backstage-playground/node_modules/axios/lib/core/Axios.js:45:41)\n    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)\n    at Object.handler (/home/runner/work/backstage-playground/backstage-playground/plugins/quarkus-backend/src/scaffolder/actions/quarkus/createApp.ts:140:30)\n    at NunjucksWorkflowRunner.executeStep (/home/runner/work/backstage-playground/backstage-playground/node_modules/@backstage/plugin-scaffolder-backend/src/scaffolder/tasks/NunjucksWorkflowRunner.ts:380:9)\n    at NunjucksWorkflowRunner.execute (/home/runner/work/backstage-playground/backstage-playground/node_modules/@backstage/plugin-scaffolder-backend/src/scaffolder/tasks/NunjucksWorkflowRunner.ts:513:9)\n    at TaskWorker.runOneTask (/home/runner/work/backstage-playground/backstage-playground/node_modules/@backstage/plugin-scaffolder-backend/src/scaffolder/tasks/TaskWorker.ts:176:26)\n    at async run (/home/runner/work/backstage-playground/backstage-playground/node_modules/p-queue/dist/index.js:163:29)",
      "stepId": "template",
      "status": "failed"
    },
    "type": "log",
    "createdAt": "2024-06-26T08:08:27.000Z"
  },