Update code block template

[hugovk]

Thanks for contribution

Please, make sure you address all the checklists (for details on how see
development documentation)!

• [n/a] ran the linter to address style issues (tox -e fix_lint)
• wrote descriptive pull request text
• ensured there are test(s) validating the fix
• [n/a] added news fragment in docs/changelog folder
• [n/a] updated/extended the documentation

The code block formatting backticks needs to be unindented to work inside a bullet point.

Demo

• without indented ✅

$ pip list
output

• with indented ❌

$ pip list
output