[Bug]: Linting rst files with vale fails

### What happened?

The vale action failed with:
```
E100 [lintRST] Runtime error

rst2html not found
```

### Version

Development (host) and target OS/architectures: Linux x86_64

Output of `bazel --version`: 7.4.1

### How to reproduce

```shell
Configure vale to lint a rst file.
```

### Any other information?

Solution is to add rst2html to PATH when running vale.