Fields declaration order really matters when using multi-variables pattern

It looks to me that the order in which the dataclass fields are declared is super important.

Example directory structure:

```
environments
dev
config
servers
server-1
server.yaml
server-2
server.yaml
server-3
server.yaml
```

Datafile definition:

```
@datafile("./environments/{self.environment}/config/servers/{self.name}/server.yaml")
class Server:
name: str
environment: str
```

When running:

```
import os

from manager.models import Cluster

if __name__ == '__main__':

clusters = list(Server.objects.all())
```

It ends up raising:

`FileNotFoundError: [Errno 2] No such file or directory: '/project/configuration/environments/server-1/config/servers/dev/server.yaml'`

This seems to come from when the manager.all method does yield self.get(*values) with values ["server-1", "dev"] which ends up building the path posted above as manager.get iterates on the fields in the order they are declared and sets the values accordingly.

If I declare:

```
@datafile("./environments/{self.environment}/config/servers/{self.name}/server.yaml")
class Server:
environment: str
name: str
```
It works.

Reproduce the example with the Server dataclass and inspect the manager.all and manager.get paths, especially how declared fields are iterated and matched with values. Done means the example builds the server.yaml path with environment and name mapped correctly without requiring a particular field declaration order.

Written by the indexing model from the issue text.