This looks better than having the header line and the sort button below
each other.

See https://github.com/mozilla/bleach/issues/698

nh3 is a small wrapper around https://crates.io/crates/ammonia - more
Rust code in Fietsboek! \o/

The default seems to be to strip unknown tags instead of replace them
with htmlentities, which is fine. Then the <script> tags are completely
gone.

Python seems to do fine, but pylint complains (probably rightfully,
since the tests do not represent packages). We lose type hinting for the
playwright_helper, but there's probably a better way to do it in the
future.

They caused issues because they might not have created the database
tables or the data directory. Since the cleanup job runs globally after
every test, it should take that into consideration and not error out.

I'd like to have more, but this is a start (and already caught some
errors, see the last two commits).