Expression syntax highlighting doesn't seem to respect comments

**Describe the bug**

Here, this line should appear as a comment:

**To Reproduce**

Here's the text:

```yaml
update-rust-toolchain:
runs-on: ubuntu-latest
# Don't run on forks; will attempt to create a PR into the fork...

# if: ${{ !github.event.pull_request.head.repo.fork }}
```

**Extension Version**
`v0.25.6`