Bump Azure.Identity from 1.20.0 to 1.21.0

---
updated-dependencies:
- dependency-name: Azure.Identity
  dependency-version: 1.21.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

Directory.Packages.props

@@ -21,7 +21,7 @@
   <ItemGroup>
     <PackageVersion Include="AspNet.Security.OAuth.GitHub" Version="10.0.0" />
     <PackageVersion Include="Azure.Extensions.AspNetCore.Configuration.Secrets" Version="1.5.0" />
-    <PackageVersion Include="Azure.Identity" Version="1.20.0" />
+    <PackageVersion Include="Azure.Identity" Version="1.21.0" />
     <PackageVersion Include="Azure.Monitor.OpenTelemetry.AspNetCore" Version="1.4.0" />
     <PackageVersion Include="Microsoft.ApplicationInsights.Profiler.AspNetCore" Version="3.0.2" />
     <PackageVersion Include="TUnit" Version="1.30.8" />