Upgrade to latest micromark (markdown only) (#18277)
Co-authored-by: fisker Cheung <lionkay@gmail.com>
Co-authored-by: fisker <lionkay@gmail.com>
Co-authored-by: Jed Fox <git@jedfox.com>
Co-authored-by: seiya <20365512+seiyab@users.noreply.github.com>