System metrics are not collected

**Describe the bug**: ...

I created a APM service on elastic cloud and using elasticapm on my backend API( FASTAPI + uvicorn + gunicorn) side
i created a client using `make_apm_client( APM_SETTINGS_CONFIG )`
and the config is:

APM_SETTINGS_CONFIG = {
'SERVICE_NAME': 'backend_fastapi',
'SECRET_TOKEN': ELASTIC_APM_SECRET_TOKEN,
'SERVER_URL': ELASTIC_APM_SERVER_URL,
'ENVIRONMENT': 'my-environment',
'ENABLED': True ,
'TRANSACTION_SAMPLE_RATE' : 0.8,
'API_REQUEST_TIME': "2m" ,
'LOG_LEVEL': 'info',
'TRANSACTION_IGNORE_URLS': ['/v1/greet/','/v1/projects/']
}

fyi , i also installed `psutil` library

**To Reproduce**

**Environment (please complete the following information)**
- OS: [e.g. Linux]: Linux
- Python version: 3.10.10
- Framework and version [e.g. Django 2.1]:FASTAPI
- APM Server version: 6.15.1
- Agent version: v8.7.0

i am using Kibana(Observability-> APM->Services->backend_fastapi->Metrics ) to view the metrics

tried DEBUG: True in the config as well but no messages are printed from apm client

thanks.