if statement in comment not shown as comment (syntax highlighting) #259

Describe the bug
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To Reproduce
Steps to reproduce the behavior:

1. Create a new workflow file and paste in the below code.
2. Observe how if: ... is highlighted incorrectly.

name: Example Workflow File
on: 
  workflow_dispatch:
jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - name: A fake step
        run: echo Hello World
# This is a block comment
# The if: with a colon after it is not highlighted properly
# An if without a colon is fine.

Expected behavior
A clear and concise description of what you expected to happen.
The if: and following text should remain grey like a comment.

Screenshots
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Extension Version
v0.26.2

Additional context
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This seems slightly related to #158