Update release.yml to use .NET 8 (#160)

Author: kailash-b

.github/workflows/release.yml

@@ -35,7 +35,7 @@ jobs:
     needs: rl-scanner
     uses: ./.github/workflows/nuget-release.yml    
     with:
-      dotnet-version: 6.0.x
+      dotnet-version: 8.0.x
       project-paths: "['src/Auth0.AspNetCore.Authentication/Auth0.AspNetCore.Authentication.csproj']"
     secrets:
       nuget-token: ${{ secrets.NUGET_APIKEY }}