Autopkgtest failure due to deprecated crypt module

[Bryce Harrington]

https://autopkgtest.ubuntu.com/results/autopkgtest-lunar/lunar/s390x/d/dovecot/20230115_035939_17364@/log.gz

autopkgtest [03:58:05]: test testmails: [-----------------------
/tmp/autopkgtest.2fs8oa/build.d2b/src/debian/tests/testmails:3: DeprecationWarning: 'crypt' is deprecated and slated for removal in Python 3.13
  import crypt
test_imap (__main__.DovecotBasics.test_imap)
Test IMAP4 protocol. ... userdel: user rlxihhoj is currently used by process 4055
ok
test_imaps (__main__.DovecotBasics.test_imaps)
Test IMAP4S protocol. ... ok
test_pop3 (__main__.DovecotBasics.test_pop3)
Test POP3 protocol. ... userdel: user drgmrajk is currently used by process 4095
ok
test_pop3s (__main__.DovecotBasics.test_pop3s)
Test POP3S protocol. ... userdel: user hedasuha is currently used by process 4114
ok

----------------------------------------------------------------------
Ran 4 tests in 78.883s

Some past autopkgtesting has shown the above failure in lunar, due to the crypt module not being found. Currently the autopkgtests are passing, however there have not been changes introduced to dovecot; perhaps something was fixed or worked around on the python side? In any case, the crypt module is marked as deprecated in 3.11 and will be removed in 3.13:

  https://docs.python.org/3/library/crypt.html#module-crypt