### 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
f.write(line)
                    except IOError as ex:
                        self.module.fail_json(msg="Failed to write to file %s: %s" % (tmp_path, to_native(ex)))
                self.module.atomic_move(tmp_path, filename)
                
                if filename in self.new_repos:
                    this_mode = self.module.params.get('mode', DEFAULT_SOURCES_PERM)
                    self.module.set_mode_if_different(filename, this_mode, False)
            else:
                del self.files[filename]
                if os.path.exists(filename):
                    os.remove(filename)
    def dump(self):
        dumpstruct = {}
        for filename, sources in self.files.items():
            if sources:
                lines = []
                for n, valid, enabled, source, comment in sources:
                    chunks = []
                    if not enabled:
                        chunks.append('# ')
                    chunks.append(source)
                    if comment:
                        chunks.append(' # ')
                        chunks.append(comment)
                    chunks.append('\n')
                    lines.append(''.join(chunks))
                dumpstruct[filename] = ''.join(lines)
        return dumpstruct
    def _choice(self, new, old):