Include prereleases for SDK installs

Author: Turnerj

.github/workflows/build.yml

@@ -35,6 +35,8 @@ jobs:
           fetch-depth: 0
       - name: "Install .NET Core SDK"
         uses: actions/setup-dotnet@v1.8.2
+        with:
+          include-prerelease: true
       - name: "Dotnet Tool Restore"
         run: dotnet tool restore
         shell: pwsh