Merge pull request #2718 from wpfcontrib/build-sdk-fixup

Add sdk.version entry to global.json

Author: rladuca

global.json

@@ -11,6 +11,9 @@
       "version": "16.1"
     }
   },
+  "sdk": {
+    "version": "5.0.100-alpha1-015515"
+  },
   "msbuild-sdks": {
     "Microsoft.DotNet.Arcade.Sdk": "5.0.0-beta.20154.1",
     "Microsoft.DotNet.Helix.Sdk": "5.0.0-beta.20154.1"