Cannot deploy OctoberCMS to Google App Engine (Flex)

I got following issue when trying to deploy my OctoberCMS+sqlite (Laravel 5.5 based) to google app engine, here is my deployment error:

...
Step #1:   - Installing october/backend (v1.0.436): Downloading (100%)
Step #1:   - Installing october/cms (v1.0.436): Downloading (100%)
Step #1:   - Installing october/system (v1.0.436): Downloading (100%)
Step #1: Generating optimized autoload files
...
Step #1: > php artisan cache:clear
Step #1: Cache cleared successfully.
Step #1: > php artisan cache:clear
Step #1: 
Step #1: In Connection.php line 664:
Step #1:                                                                                
Step #1:   could not find driver (SQL: select * from "system_settings" where "item" =   
Step #1:   vojtasvoboda_errorlogger_settings limit 1)                                   
Step #1:                                                                                
Step #1: 
Step #1: In PDOConnection.php line 47:
Step #1:                          
Step #1:   could not find driver  
Step #1:                          
Step #1: 
Step #1: In PDOConnection.php line 43:
Step #1:                          
Step #1:   could not find driver  
Step #1:                          
Step #1: 
Step #1: Script php artisan cache:clear handling the post-install-cmd event returned with error code 1
Step #1: The command '/bin/sh -c /build-scripts/composer.sh' returned a non-zero code: 1
Finished Step #1
ERROR
ERROR: build step 1 "gcr.io/cloud-builders/docker@sha256:5836cd0f940f2f1a912b8fee4c74e5f1a84df92aab557c608a94e171e9df8d46" failed: exit status 1
Step #1: 
------------------------------------------------------------------------------------------------------------------------------------------------------

ERROR: (gcloud.app.deploy) Cloud build failed. Check logs at https://console.cloud.google.com/gcr/builds/23c79228-9500-4c42-8bea-9b8076e30c42?project=1055473064866 Failure status: UNKNOWN: Error Response: [2] Build failed; check build logs for details

Here is my app.yaml

runtime: php
env: flex

runtime_config:
  document_root: .

# Ensure we skip ".env", which is only for local development
skip_files:
  - .env
  - Dockerfile
  - docker-compose.yml

env_variables:
  # Put production environment variables here.
  APP_LOG: errorlog
  #APP_KEY: LCG9E1xG5FQDMNauR8wWW3GTyB6Tj6Nv
  STORAGE_DIR: /tmp

Here is my database:

...
'default' => env('DB_CONNECTION', 'sqlite'),
...

'sqlite' => [
    'driver'   => 'sqlite',
    'database' => env('DB_DATABASE', 'storage/database.sqlite'),
    'prefix'   => '',
],
    ...

My GAE is Flexible env and it should be able to use Framework and CMS there, but unfortunately this error don't let me install this Laravel based CMS on this service.

Any help regarding this will be extremely appreciated. thanks

via Chebli Mohamed