Fix CI, in another way

[muzimuzhi]

The GitHub Docs source has taken the <code>...&lt;...&gt;...</code> to `...<...>...` changes 4 months ago, see github/docs@a15d261.

[rhysd]

Thank you for taking time to look into this.

However this is not a fix but a workaround not to make CI fail. The root cause is that goldmark has changed the behavior of Node.Text.

yuin/goldmark#471

This PR modifies the test data not to hit this issue. So after merging this PR, the issue is still there. You'll find that Node.Text calls cause bunch of warnings from staticcheck due to deprecation if you update goldmark to v1.7.8.

Making the test data follow the latest document is another maintenance work.

Since I already know the reason, I'll add a fix for this.

[rhysd]

I used the idea of 0c5f33d at 763f886 so I credit you at the commit.

[muzimuzhi]

Thank you. 😄