chore(csharp): Bump OpenTelemetry from 1.12.0 to 1.15.2

---
updated-dependencies:
- dependency-name: OpenTelemetry
  dependency-version: 1.15.2
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

csharp/Directory.Packages.props

@@ -40,7 +40,7 @@
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.4.0" />
     <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="10.0.201" />
     <PackageVersion Include="Moq" Version="4.20.72" />
-    <PackageVersion Include="OpenTelemetry" Version="1.12.0" />
+    <PackageVersion Include="OpenTelemetry" Version="1.15.2" />
     <PackageVersion Include="OpenTelemetry.Exporter.Console" Version="1.12.0" />
     <PackageVersion Include="OpenTelemetry.Exporter.OpenTelemetryProtocol" Version="1.12.0" />
     <PackageVersion Include="System.Diagnostics.DiagnosticSource" Version="9.0.6" />