Support Serilog 3.0.0

### Describe the feature

Serilog 3.0.0 has been released on June 20th 1:01 AM GMT+2. Changelog: https://github.com/serilog/serilog/releases/tag/v3.0.0

`AWS.Logger.SeriLog` currently supports Serilog v2.6.0 and up.

The major version release of Serilog does come with breaking changes.

### Use Case

Aiming to keep up with current developments in dependencies we use, to security minimize risks and benefiting from performance improvements.

### Proposed Solution

Update the dependency on Serilog to version 3.0.0 and fix breaking changes.

### Other Information

_No response_

### Acknowledgements

- [ ] I may be able to implement this feature request
- [X] This feature might incur a breaking change

### AWS .NET SDK and/or Package version used

AWS.Logger.SeriLog v3.2.0

### Targeted .NET Platform

.NET6

### Operating System and version

AmazonLinux, Windows 10

Start by reviewing the Serilog 3.0.0 changelog linked in the issue and locating the AWS.Logger.SeriLog dependency and its tests. Identify the breaking changes affecting this package, then verify that the dependency targets Serilog 3.0.0 and the existing test suite passes.

Written by the indexing model from the issue text.