A config dict passed to create_request seems to be sent incorrectly

Thank you for the amazing lib! I am facing an issue though,

If I send in this request:
```
repository.create_request(
message="test env vars through API",
branch="env-tests",
config={"env": {"global": ["REGISTRY=PROD"]}},
)
```

I get this response back:
```
"request": {
"repository": {
"id": xxxx,
"owner_name": "xxxx",
"name": "xxxx"
},
"user": {
"id": xxxx
},
"id": xxxx,
"message": "test env vars through API",
"branch": "env-tests",
"config": "env"
```

The ` "config": "env"` seems to be truncated. It should be sent like this
```
"config": {
"env": {
"global": [
"REGISTRY=PROD"
]
}
}
```

:( Any thoughts?