Bump Azure.Identity from 1.13.2 to 1.15.0

---
updated-dependencies:
- dependency-name: Azure.Identity
  dependency-version: 1.15.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

user-auth/GraphTutorial/GraphTutorial.csproj

@@ -15,7 +15,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Azure.Identity" Version="1.13.2" />
+    <PackageReference Include="Azure.Identity" Version="1.15.0" />
     <PackageReference Include="Microsoft.Extensions.Configuration.Binder" Version="8.0.2" />
     <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="8.0.1" />
     <PackageReference Include="Microsoft.Extensions.Configuration.UserSecrets" Version="8.0.1" />