NGINX Unit, Fastapi : The module to run \"python 3.8\" is not found among the available application modules

Question

i'm following the query of the documentation of nginx unit with fastapi => https://unit.nginx.org/howto/fastapi/

I ran this query : curl -X PUT --data-binary @config.json --unix-socket /var/run/control.unit.sock http://localhost/config/

but i got an error :

"error": "Invalid configuration.", "detail": "The module to run "python 3.8" is not found among the available application modules."

my config file (config.json) look like this :

{
 "listeners": {
 "*:80": {
 "pass": "applications/fastapi"
}
},

 "applications": {
    "fastapi": {
        "type": "python 3.8",
        "path": "/home/ubuntu/inference1",
        "home": "/home/ubuntu/anaconda3/envs/inference1/bin",
        "module": "application",
        "callable": "app"
    }
 }
}

the command line query i run to see the modules : ls /usr/lib/unit/modules gives me :

java11.unit.so perl.unit.so python2.7.unit.so python3.7.unit.so ruby.unit.so java8.unit.so php.unit.so python3.6.unit.so python3.8.unit.so

If someone knows why the query is returning me the error i cannot find it :'(