Bug#1010279: python-iso8601: please make the build reproducible

[James Addison]

Source: python-iso8601
Followup-For: Bug #1010279
X-Debbugs-Cc: lamby at debian.org, reproducible-bugs at lists.alioth.debian.org

>From some recent build results, it seems there is a '.hypothesis' directory
that is also created within the project's directory at build-time, so it would
also be worth filtering that directory in addition to the '.pytest_cache' dir.

After searching around on sources.debian.org to find out how other packages
handle extraneous files like these, I learned of the 'debian/clean' file; that
might be a slightly neater (fewer scripted statements) exclusion approach.

Either way: I think that when building with dh-python/6.20231204 onwards, these
directories are automatically excluded from the binary package thanks to the
fix for #1056291 (an obscure filesystem os.walk bug in dh-python).