Review and update .gitignore in dotnet_sdk

[ranaandixon704-eng]

The .gitignore file in the dotnet_sdk/ directory currently includes the following rules:

/.bundle/
!.bundle/config
/.env
/tmp
/dependabot-*.gem

Please review and update the ignore rules if needed. Ensure that only appropriate files and folders are excluded from version control, especially for .NET SDK-related development and builds. Consider typical .NET exclusions and confirm that all necessary files for CI/CD, testing, and package publishing are tracked.

Source: https://github.com/dependabot/dependabot-core/blob/c093035965a062ab2d8f77a5c5e506c9b81b6cc0/dotnet_sdk/.gitignore