Update Amazon.Lambda.Core to 2.5.0 to support SnapStart

[AlexDaines]

Issue: V1651929313

Description

This change updates the Amazon.Lambda.Core package reference to version 2.5.0 across the Lambda Test Tool and its test projects to support SnapStart functionality.

Motivation and Context

When using the Lambda Test Tool with functions that utilize SnapStart features, users encounter a TypeLoadException because the tool is using an older version of Amazon.Lambda.Core that doesn't include the SnapStart type. This update ensures compatibility with Lambda functions using SnapStart functionality.

Testing

1. Created a test Lambda function that uses SnapStart functionality
2. Initially reproduced the error with the current version
3. Updated package references to 2.5.0
4. Manually copied the updated DLL
5. Verified the function now executes without SnapStart-related errors

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project
• My change requires a change to the documentation
• I have updated the documentation accordingly
• I have read the README document
• I have added tests to cover my changes
• All new and existing tests passed

License

• I confirm that this pull request can be released under the Apache 2 license

[normj]

I added the change log file and change the target branch to dev.