Pulp

The change in #7700 introduced a dependency on the gpg binary.

We should install this like any other distro / OS package.

Without gpg installed, a failure is happening during database migrations.

 "pulp [None]: gnupg:ERROR: Unable to run gpg (gpg) - it may not be available.
Traceback (most recent call last):
 File \"/usr/local/lib/pulp/lib/python3.7/site-packages/gnupg.py\", line 854, in __init__
    p = self._open_subprocess([\"--version\"])
  File \"/usr/local/lib/pulp/lib/python3.7/site-packages/gnupg.py\", line 935, in _open_subprocess
    startupinfo=si)
  File \"/usr/lib/python3.7/subprocess.py\", line 775, in __init__
    restore_signals, start_new_session)
  File \"/usr/lib/python3.7/subprocess.py\", line 1522, in _execute_child
    raise child_exception_type(errno_num, err_msg, err_filename)
FileNotFoundError: [Errno 2] No such file or directory: 'gpg': 'gpg'
Traceback (most recent call last):
  File \"/usr/local/lib/pulp/lib/python3.7/site-packages/gnupg.py\", line 854, in __init__