Bump OpenTelemetry.Exporter.OpenTelemetryProtocol

Bumps [OpenTelemetry.Exporter.OpenTelemetryProtocol](https://github.com/open-telemetry/opentelemetry-dotnet) from 1.4.0-beta.3 to 1.6.0.
- [Release notes](https://github.com/open-telemetry/opentelemetry-dotnet/releases)
- [Commits](open-telemetry/opentelemetry-dotnet@core-1.4.0-beta.3...core-1.6.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

tests/Proto.Cluster.Tests/Proto.Cluster.Tests.csproj

@@ -16,7 +16,7 @@
         <PackageReference Include="Grpc.Tools" Version="2.51.0" PrivateAssets="All" />
         <PackageReference Include="IsExternalInit.System.Runtime.CompilerServices" Version="1.0.0" />
         <PackageReference Include="OpenTelemetry.Exporter.Jaeger" Version="1.4.0-beta.3" />
-        <PackageReference Include="OpenTelemetry.Exporter.OpenTelemetryProtocol" Version="1.4.0-beta.3" />
+        <PackageReference Include="OpenTelemetry.Exporter.OpenTelemetryProtocol" Version="1.6.0" />
         <PackageReference Include="OpenTelemetry.Exporter.OpenTelemetryProtocol.Logs" Version="1.4.0-beta.3" />
         <PackageReference Include="System.Interactive.Async" Version="6.0.1" />
     </ItemGroup>