fix: restart dovecot after package replacement

[Retengart]

Summary

• track Dovecot package replacement separately from config-driven restart logic in cmdeploy
• explicitly restart Dovecot after package changes even when policy-rc.d blocks package-triggered restarts
• add unit coverage for package-change restart behavior and an online regression for stale deleted Dovecot binaries

Test Plan

• venv/bin/pytest cmdeploy/src/cmdeploy/tests/test_dovecot_deployer.py -v
• venv/bin/pytest cmdeploy/src/cmdeploy/tests/test_cmdeploy.py cmdeploy/src/cmdeploy/tests/test_helpers.py cmdeploy/src/cmdeploy/tests/test_rshell.py -v
• venv/bin/pytest cmdeploy/src/cmdeploy/tests/online/test_1_basic.py::test_dovecot_main_process_matches_installed_binary -v
• venv/bin/pytest cmdeploy/src/cmdeploy/tests/online/test_0_login.py::test_login_basic_functioning -v
• ruff check cmdeploy/src/cmdeploy/dovecot/deployer.py cmdeploy/src/cmdeploy/tests/test_dovecot_deployer.py

[Retengart]

@missytake , Can you take a look at what's with /home/runner/.ssh/id_ed25519 and restart the deployment?

[j4n]

Looks good mostly, thank you :)

[Retengart]

Merged main into fix-dovecot to resolve the Dovecot deployer conflict. Kept both behaviors in install(): restart intent after package replacement and the new pin-dovecot apt preferences file. Added regression coverage for the pinning path and reran venv/bin/pytest cmdeploy/src/cmdeploy/tests/test_dovecot_deployer.py cmdeploy/src/cmdeploy/tests/test_cmdeploy.py cmdeploy/src/cmdeploy/tests/test_helpers.py cmdeploy/src/cmdeploy/tests/test_rshell.py --import-mode=importlib (19 passed). Ready for re-review.

[j4n]

looks good, one minor remark still left from the original list.

[j4n]

This test is about the archive-vs-epoch version split. But name (pyinfra unit) and cache_time (calculated twice) are unrelatedand if any of those change, this test breaks with a misleading failure pointing at a version-separation test. Maybe:

assert len(downloads) == 1
assert archive_version in downloads[0]["src"]
assert archive_version in downloads[0]["dest"]
assert dovecot_deployer.DOVECOT_PACKAGE_VERSION not in downloads[0]["src"]
assert dovecot_deployer.DOVECOT_PACKAGE_VERSION not in deb