Updated a dotnet Notebook for AI Kernel setting using Settings.LoadFromFile()

[blueviggen]

Motivation and Context

Description

I made a small change in the 01-basic-loading-the-kernel notebook (for dotnet) to make it consistent with other dotnet notebooks by using Settings.LoadFromFile(). (https://github.com/microsoft/semantic-kernel/tree/main/samples/notebooks/dotnet/01-basic-loading-the-kernel.ipynb)

Contribution Checklist

• [X ] The code builds clean without any errors or warnings
• [X ] The PR follows SK Contribution Guidelines (https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
• [X ] The code follows the .NET coding conventions (https://learn.microsoft.com/dotnet/csharp/fundamentals/coding-style/coding-conventions) verified with dotnet format
• [ ] All unit tests pass, and I have added new tests where possible
• [ X] I didn't break anyone :smile: