MINOR: [C#] Bump Grpc.Tools from 2.56.2 to 2.57.0 in /csharp (#37154)

Bumps [Grpc.Tools](https://github.com/grpc/grpc) from 2.56.2 to 2.57.0.
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Authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Signed-off-by: Sutou Kouhei <[email protected]>

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

@@ -7,7 +7,7 @@
   <ItemGroup>
     <PackageReference Include="Google.Protobuf" Version="3.24.0" />
     <PackageReference Include="Grpc.Net.Client" Version="2.55.0" />
-    <PackageReference Include="Grpc.Tools" Version="2.56.2" PrivateAssets="All" />
+    <PackageReference Include="Grpc.Tools" Version="2.57.0" PrivateAssets="All" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFramework)'=='netstandard2.0'">