Net48 is not compatible with WCF6.0 packages when projects specify multiple target frameworks

**Describe the bug**
Specifying multiple target frameworks Net48 and Net6.0 in the project, adding a WCF service reference, and then building the solution, I get an error that Net48 is not compatible with the WCF6.0 package.

**To Reproduce**
Steps to reproduce the behavior:
1. Create Net6.0 TargetFramework project, e.g., Console App
2. Open .csproj file, change net6.0 to net6.0;net48, delete ImplicitUsings and Nullable those two properties
3. Go to Program.cs file, add the following sample code. Save all changes.
4. Add WCF Service reference
5. Build solution

**Expected behavior**
The code is generated without error and the project builds successfully.