Fix DeprecationWarning: openfeature.provider.provider is deprecated, use openfeature.provider instead

Please, in the `providers.py` file, change the import
```python
# Deprecated
# from openfeature.provider import Metadata
# from openfeature.provider.provider import AbstractProvider

# Updated
from openfeature.provider import Metadata, AbstractProvider
```

This will solve the following warning:

```
DeprecationWarning: openfeature.provider.provider is deprecated, use openfeature.provider instead
```

Thank you very much!

Open providers.py and locate the deprecated import from openfeature.provider.provider. Confirm the warning no longer occurs after the import uses openfeature.provider, and verify the repository's existing checks if available.

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