Adding publishing support

MSBuild.Sdk.SqlProj 1.2.0 introduces support for publishing a project to a local SQL Server instance. On Windows running dotnet publish should work out-of-the-box if you have a default SQL Server instance installed on your machine. On Mac and Linux we cannot use Windows authentication, so you'll need to specify a username and password. Checkout the README for more details on how publishing works and how you can customize the process to suit your needs.

IMPORTANT: With this release we've dropped support for .NET Core 2.2 since that version is end-of-life. You should upgrade your projects to .NET Core 3.1.