当我尝试在gitlab-ci上使用serverless将我的flask应用部署为lambda函数时，出现以下错误。

Error: spawn python3.8 ENOENT
    at Process.ChildProcess._handle.onexit (internal/child_process.js:268:19)
    at onErrorNT (internal/child_process.js:470:16)
    at processTicksAndRejections (internal/process/task_queues.js:84:21)
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1

然而，当我在本地运行命令sls deploy时，它工作正常。
下面是我的serverless.yml：

service: serverless-flask

plugins:
  - serverless-python-requirements
  - serverless-wsgi

custom:
  wsgi:
    app: app.app
    packRequirements: false
  pythonRequirements:
    dockerizePip: non-linux

provider:
  name: aws
  runtime: python3.8
  region: eu-west-3
  memorySize: 256
  timeout: 15

functions:
  app:
    handler: wsgi_handler.handler
    environment: ${file(env.${opt:stage, self:provider.stage}.json)}
    events:
      - http: ANY /
      - http: ANY /{proxy+}

下面是我的gitlab-ci.yml：

image: ubuntu:latest

stages:
  - deploy

dev:
  only:
    - develop
  stage: deploy
  before_script:
    - apt-get update
    - ARG DEBIAN_FRONTEND=noninteractive apt-get install -y software-properties-common && add-apt-repository ppa:deadsnakes/ppa && apt-get update && apt-get install -y python3.8 python3-pip && rm -rf /var/lib/apt/lists/*
    - apt update
    - apt install -y nodejs npm
    - npm install -g serverless
    - npm install
  script:
    - serverless deploy --stage dev
  environment: dev

我尝试了不同的docker图像，如python，节点，ubuntu，但我不能使它工作。