### Summary

The `apt_repository` will fail with a somewhat confusing error if gnugp, and dirmngr manager are not installed.  Neither of these packages are Required/Essential/Important, and may not be already installed in minimal systems that you might want to run `apt_repository` on.

The fix might be to just include `gnupg` in the requirements section of the docs.

### Issue Type

Documentation Report

### Component Name

apt_repository

### Ansible Version

```console
$  ansible --version
ansible [core 2.11.4]
  config file = ...
  configured module search path = ...
  ansible python module location = ...
  ansible collection location = ...
  executable location = /usr/local/bin/ansible
  python version = 3.9.2 (default, Feb 28 2021, 17:03:44) [GCC 10.2.1 20210110]
  jinja version = 3.0.1
  libyaml = True
```


### Configuration

```console
$ ansible-config dump --only-changed
```


### OS / Environment

Mostly a docs issue so this is N/A. But apt_repository applies to Debian, Ubuntu, and forks.

### Additional Information

Tells people that need gnupg when using apt_repository.

### Code of Conduct

- [X] I agree to follow the Ansible Code of Conduct
import time
from ansible.module_utils.basic import AnsibleModule
from ansible.module_utils.common.respawn import has_respawned, probe_interpreters_for_module, respawn_module
from ansible.module_utils._text import to_native
from ansible.module_utils.six import PY3
from ansible.module_utils.urls import fetch_url
try:
    import apt
    import apt_pkg
    import aptsources.distro as aptsources_distro
    distro = aptsources_distro.get_distro()
    HAVE_PYTHON_APT = True
except ImportError:
    apt = apt_pkg = aptsources_distro = distro = None
    HAVE_PYTHON_APT = False
DEFAULT_SOURCES_PERM = 0o0644
VALID_SOURCE_TYPES = ('deb', 'deb-src')
def install_python_apt(module, apt_pkg_name):
    if not module.check_mode:
        apt_get_path = module.get_bin_path('apt-get')
        if apt_get_path:
            rc, so, se = module.run_command([apt_get_path, 'update'])
            if rc != 0:
                module.fail_json(msg="Failed to auto-install %s. Error was: '%s'" % (apt_pkg_name, se.strip()))
            rc, so, se = module.run_command([apt_get_path, 'install', apt_pkg_name, '-y', '-q'])
            if rc != 0:
                module.fail_json(msg="Failed to auto-install %s. Error was: '%s'" % (apt_pkg_name, se.strip()))
    else:
        module.fail_json(msg="%s must be installed to use check mode" % apt_pkg_name)
class InvalidSource(Exception):