add gpg package to build - ubuntu-22.04 python 3.13 skips pgp tests. The 3.13 tests on ubuntu-22.04 report that PGP tests are skipped because: SKIPPED [1] test/test_mailgw.py:296: Skipping PGP tests: 'gpg' not installed the same tests pass under python 3.12 and ubuntu-22.04. Under both versions, the gpg build and install report no issues. Add the gpg package to see if it fixes it. (Log used: https://github.com/roundup-tracker/roundup/actions/runs/11633664792/job/32399246320)