Specify SDK version in global.json

[rkm]

Proposed Changes

This patch adds a global.json file which specifies the dotnet SDK version to build with. This has the effect of syncing the version of the SDK that is used for local development and all CI checks (including LGTM which is currently specified separately).

The version suggested in this PR (5.0.302) is quite new, so we could roll this back if some developers don't have this installed yet.

Types of changes

What types of changes does your code introduce? Tick all that apply.

• Bugfix (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 not work as expected)
• Documentation-Only Update (if none of the other choices apply)
  • In this case, ensure that the message of the head commit from the source branch is prefixed with [skip ci]

Checklist

By opening this PR, I confirm that I have:

• Reviewed the contributing guidelines for this repository
• Ensured that the PR branch is in sync with the target branch (i.e. it is automatically merge-able)
• Updated any relevant API documentation
• Created or updated any tests if relevant
• Created a news file
  • NOTE: This must include any changes to any of the following files: default.yaml, any of the RabbitMQ server configurations, GlobalOptions.cs
• Listed myself in the CONTRIBUTORS file 🚀
• Requested a review by one of the repository maintainers

Issues

[coveralls]

Coverage decreased (-0.01%) to 49.381% when pulling 253b7c5 on feature/dotnet-sdk-specify-version into a258b05 on master.