Docs: correct Python console block type

[sethfischer]

Correct block type to avoid failing test such as in #9879:

blacken-docs.............................................................Failed
- hook id: blacken-docs
- exit code: 1

docs/user/build-customization.rst:122: code block parse error Cannot parse: 1:0: >>> sum(list('skip'.encode('ascii')))

pre-commit: exit 1 (27.71 seconds) /home/circleci/project> pre-commit run --from-ref main --to-ref HEAD pid=311
  pre-commit: FAIL code 1 (32.93=setup[5.22]+cmd[27.71] seconds)
  evaluation failed :( (33.28 seconds)

Exited with code exit status 1

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📚 Documentation previews 📚

• User's documentation (docs): https://docs--9880.org.readthedocs.build/en/9880/

• Developer's documentation (dev): https://dev--9880.org.readthedocs.build/en/9880/

[benjaoming]

I had a bunch of notifications at the same time and somehow missed this one (and did EXACTLY the same in #9884). Superb @sethfischer !