MINOR: [C#] Bump System.ValueTuple from 4.5.0 to 4.6.1

---
updated-dependencies:
- dependency-name: System.ValueTuple
  dependency-version: 4.6.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

csharp/src/Apache.Arrow/Apache.Arrow.csproj

@@ -16,7 +16,7 @@
     <PackageReference Include="System.Memory" Version="4.6.0" />
     <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="6.1.0" />
     <PackageReference Include="System.Threading.Tasks.Extensions" Version="4.6.0" />
-    <PackageReference Include="System.ValueTuple" Version="4.5.0" />
+    <PackageReference Include="System.ValueTuple" Version="4.6.1" />
   </ItemGroup>
 
   <ItemGroup>