Guess what?!
A new upstream version of Pygments is now available: 2.16.1.
Wikimedia production wikis are currently using 2.15.1 via shellbox. The beta cluster is using 2.15.0 via the bundled version of Pygments in the extension. Upstream's change log for 2.15.1-2.16.1 includes updates for the wikitext lexer from @Diskdance.
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