Add missing ref to share project

- Need this to include TestClassAttribute.
- Bump version to 3.0.

Author: josesimoes

source/UnitTestLauncher/nanoFramework.UnitTestLauncher.nfproj

@@ -44,6 +44,7 @@
       <HintPath>..\..\packages\nanoFramework.CoreLibrary.1.15.5\lib\mscorlib.dll</HintPath>
     </Reference>
   </ItemGroup>
+  <Import Project="..\TestFrameworkShared\TestFrameworkShared.projitems" Label="Shared" />
   <Import Project="$(NanoFrameworkProjectSystemPath)NFProjectSystem.CSharp.targets" Condition="Exists('$(NanoFrameworkProjectSystemPath)NFProjectSystem.CSharp.targets')" />
   <ProjectExtensions>
     <ProjectCapabilities>

version.json

@@ -1,6 +1,6 @@
 {
   "$schema": "https://raw.githubusercontent.com/dotnet/Nerdbank.GitVersioning/master/src/NerdBank.GitVersioning/version.schema.json",
-  "version": "2.1",
+  "version": "3.0",
   "assemblyVersion": {
     "precision": "build"
   },
@@ -23,4 +23,4 @@
     "firstUnstableTag": "preview",
     "versionIncrement": "build"
   }
-}
+}