Bump Grpc.Tools from 2.67.0 to 2.68.1 (#334)

Bumps [Grpc.Tools](https://github.com/grpc/grpc) from 2.67.0 to 2.68.1.
- [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] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Directory.Packages.props

@@ -12,7 +12,7 @@
     <PackageVersion Include="Google.Protobuf" Version="3.29.1" />
     <PackageVersion Include="Grpc.AspNetCore" Version="2.67.0" />
     <PackageVersion Include="Grpc.Net.Client" Version="2.67.0" />
-    <PackageVersion Include="Grpc.Tools" Version="2.67.0" />
+    <PackageVersion Include="Grpc.Tools" Version="2.68.1" />
     <PackageVersion Include="Microsoft.AspNetCore.TestHost" Version="8.0.10" />
     <PackageVersion Include="Microsoft.Bcl.AsyncInterfaces" Version="8.0.0" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />