2.21.0-beta3 (2.21.0.00401)

• Remove two unnecessary .NET Standard 1.x dependencies.
• Address vulnerability in Newtonsoft.Json (GHSA-5crp-9r3c-p9vr).
  Mitigation is to upgrade dependencies in Microsoft.ApplicationInsights.AspNetCore (#2615)
  • Upgrade Microsoft.Extensions.Configuration.Json from v2.1.0 to v3.1.0.
  • Upgrade System.Text.Encodings.Web from 4.5.1 to 4.7.2.