To simplify the library (removing ifdefs), reduce package size, and possibly enable new features (e.g., pipelines, Utf8String?) remove support for the following platforms:

• netstandard1.3 done in Remove netstandard1.3 support #1031
• .NET 4.5.x done in Remove net45 support #1209
• .NET 4.6.x

Should the minimum .NET Framework version be updated to 4.8, or stay at 4.7.1? Or dropped entirely?

Right now System.IO.Pipelines still supports netstandard1.3, so dropping old platforms may not strictly be necessary.

This is also a current advantage of MySqlConnector over MySql.Data: we support netstandard1.3 (vs netstandard2.0) and net45 (vs net452).