Update target platforms:

- net452
- net462
- net472
- net48
- netstandard2.0 (.NET Core 2+)

Author: grandsilence

Leaf.xNet/Leaf.xNet.csproj

@@ -11,7 +11,7 @@
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <RootNamespace>Leaf.xNet</RootNamespace>
     <AssemblyName>Leaf.xNet</AssemblyName>
-    <TargetFrameworks>net472;netstandard2.0</TargetFrameworks>
+    <TargetFrameworks>net452;net462;net472;net48;netstandard2.0</TargetFrameworks>
     <FileAlignment>512</FileAlignment>
     <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
     <Authors>Grand Silence</Authors>