Upgrade from `net6.0` to LTS (or STS) image tag

The following Dockerfile(s) target a .NET version that's no longer supported.
This is an auto-generated issue, detailed and discussed in [dotnet/docs#22271](https://github.com/dotnet/docs/issues/22271).

| Target version | End of life | Release notes | Nearest LTS TFM version |
| --- | --- | --- | --- |
| `net6.0` | November, 12 2024 | [net6.0 release notes](https://builds.dotnet.microsoft.com/dotnet/release-metadata/6.0/releases.json) | `net8.0` |

- [ ] github-actions/DotNet.GitHubAction/Dockerfile
- [ ] github-actions/DotNet.GitHubAction/Dockerfile
- [ ] github-actions/DotNet.GitHubAction/Dockerfile
- [ ] github-actions/DotNet.GitHubAction/Dockerfile
- [ ] orleans/Voting/Dockerfile
- [ ] orleans/Voting/Dockerfile
- [ ] orleans/Voting/Dockerfile
- [ ] orleans/Voting/Dockerfile

Consider upgrading Dockerfile images to either the Standard Term Support (STS) or Long Term Support (LTS) versions.

If any of these Dockerfile(s) listed in this issue are intentionally targeting an unsupported version,
you can optionally configure to ignore these results in future automation executions.
Create a (or update the) *dotnet-versionsweeper.json* file at the root of the repository and
add an `ignore` entry following the
[globbing patterns detailed here](https://learn.microsoft.com/dotnet/core/extensions/file-globbing).

```json
{
"ignore": [
"**/path/to/Dockerfile"
]
}
```