chore(csharp): Bump System.Diagnostics.DiagnosticSource 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-name: System.Diagnostics.DiagnosticSource
  dependency-version: 9.0.8
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
diff --git a/csharp/src/Apache.Arrow.Adbc/Apache.Arrow.Adbc.csproj b/csharp/src/Apache.Arrow.Adbc/Apache.Arrow.Adbc.csproj
index 005a5cd..c3463a7 100644
--- a/csharp/src/Apache.Arrow.Adbc/Apache.Arrow.Adbc.csproj
+++ b/csharp/src/Apache.Arrow.Adbc/Apache.Arrow.Adbc.csproj
@@ -7,7 +7,7 @@
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="Apache.Arrow" Version="20.0.0" />
-    <PackageReference Include="System.Diagnostics.DiagnosticSource" Version="9.0.6" />
+    <PackageReference Include="System.Diagnostics.DiagnosticSource" Version="9.0.8" />
   </ItemGroup>
   <ItemGroup Condition="!$([MSBuild]::IsTargetFrameworkCompatible($(TargetFramework), 'net6.0'))">
     <PackageReference Include="System.Text.Json" Version="8.0.5" />
diff --git a/csharp/test/Apache.Arrow.Adbc.Tests/Apache.Arrow.Adbc.Tests.csproj b/csharp/test/Apache.Arrow.Adbc.Tests/Apache.Arrow.Adbc.Tests.csproj
index 2432e78..3612118 100644
--- a/csharp/test/Apache.Arrow.Adbc.Tests/Apache.Arrow.Adbc.Tests.csproj
+++ b/csharp/test/Apache.Arrow.Adbc.Tests/Apache.Arrow.Adbc.Tests.csproj
@@ -12,7 +12,7 @@
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
     <PackageReference Include="Moq" Version="4.20.72" />
     <PackageReference Include="OpenTelemetry" Version="1.12.0" />
-    <PackageReference Include="System.Diagnostics.DiagnosticSource" Version="9.0.6" />
+    <PackageReference Include="System.Diagnostics.DiagnosticSource" Version="9.0.8" />
     <PackageReference Include="System.Text.Json" Version="8.0.5" />
     <PackageReference Include="xunit" Version="2.9.3" />
     <PackageReference Include="xunit.runner.visualstudio" Version="3.1.1">