The following actions uses node12 which is deprecated and will be forced to run on node16: actions/checkout@v2, actions/setup-dotnet@v1. For more info: https://github.blog/changelog/2023-06-13-github-actions-all-actions-will-run-on-node16-instead-of-node12-by-default/

The annotation for nullable reference types should only be used in code within a '#nullable' annotations context.