MINOR: [C#] Bump Grpc.Tools from 2.66.0 to 2.67.0 in /csharp

Bumps [Grpc.Tools](https://github.com/grpc/grpc) from 2.66.0 to 2.67.0.
- [Release notes](https://github.com/grpc/grpc/releases)
- [Changelog](https://github.com/grpc/grpc/blob/master/doc/grpc_release_schedule.md)
- [Commits](https://github.com/grpc/grpc/commits)

---
updated-dependencies:
- dependency-name: Grpc.Tools
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

csharp/src/Apache.Arrow.Flight.Sql/Apache.Arrow.Flight.Sql.csproj

@@ -5,7 +5,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Grpc.Tools" Version="2.66.0" PrivateAssets="All" />
+    <PackageReference Include="Grpc.Tools" Version="2.67.0" PrivateAssets="All" />
   </ItemGroup>
 
   <ItemGroup>

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

@@ -7,7 +7,7 @@
   <ItemGroup>
     <PackageReference Include="Google.Protobuf" Version="3.28.2" />
     <PackageReference Include="Grpc.Net.Client" Version="2.65.0" />
-    <PackageReference Include="Grpc.Tools" Version="2.66.0" PrivateAssets="All" />
+    <PackageReference Include="Grpc.Tools" Version="2.67.0" PrivateAssets="All" />
     <PackageReference Include="System.Memory" Version="4.5.5" />
   </ItemGroup>