Hi,

Whilst working on the Reproducible Builds effort [0], we noticed that
dkimpy could not be built reproducibly.

This is because the testsuite bumps the modification time of the
/dkim/tests/ directory to the current time (which later gets clamped
back to SOURCE_DATE_EPOCH), so if the tests are skipped via nocheck,
then this directory will retain its original, upstream timestamp.

Instead of saving upstream's original timestamp and restoring that
later, I've attached a patch to always set the mtime of this directory
to SOURCE_DATE_EPOCH regardless of whether the tests are run or not.

 [0] https://reproducible-builds.org/


Regards,