Upgrade .NET Standard 1.1 on package to 2.0 and drop .NET Framework 4.0.
Because .NET Framework 4.0 Implements .NET Standard 2.0 it should be ok to drop it and the .NET Standard 1.1 targets (besides they are End of Life anyways).
However I could also argue with dropping all but .NET 6 support too but that would make all users angry so let's only target .NET Standard 2.0 and .NET 6 to make them all happy and to simplify the package some.
Even I had to make this hard cut on my 14+ nuget packages to make them more easier to maintain (I think it is ok for forcing developers using .NET Standard 1.x to upgrade to something that implements 2.x).