Bump the dotnet group with 1 update (#47779)

Bumps System.Diagnostics.DiagnosticSource from 9.0.7 to 9.0.8

---
updated-dependencies:
- dependency-name: System.Diagnostics.DiagnosticSource
  dependency-version: 9.0.8
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: dotnet
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

docs/core/diagnostics/snippets/Metrics/metric-instr.csproj

@@ -9,7 +9,7 @@
 
   <ItemGroup>
     <PackageReference Include="OpenTelemetry.Exporter.Prometheus.HttpListener" Version="1.6.0-rc.1" />
-    <PackageReference Include="System.Diagnostics.DiagnosticSource" Version="9.0.7" />
+    <PackageReference Include="System.Diagnostics.DiagnosticSource" Version="9.0.8" />
   </ItemGroup>
 
 </Project>