make paket backwards compatible for netcoreapp5.0 - references #3896

Author: forki

src/Paket.Core/Versioning/FrameworkHandling.fs

@@ -796,6 +796,7 @@ module FrameworkDetection =
             // http://nugettoolsdev.azurewebsites.net/4.0.0/parse-framework?framework=.NETPortable%2CVersion%3Dv0.0%2CProfile%3DProfile2
             let result =
                 match path with
+                | "netcoreapp5.0" -> Some (DotNetFramework FrameworkVersion.V5)
                 | "net35-Unity Web v3.5" ->  Some (DotNetUnity DotNetUnityVersion.V3_5_Web)
                 | "net35-Unity Micro v3.5" -> Some (DotNetUnity DotNetUnityVersion.V3_5_Micro)
                 | "net35-Unity Subset v3.5" -> Some (DotNetUnity DotNetUnityVersion.V3_5_Subset)