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!

開啟 providers.py 並找到來自 openfeature.provider.provider 的已棄用匯入。確認匯入使用 openfeature.provider 後不再出現警告，並在可用的情況下驗證 repository 中現有的檢查。

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