### 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
'''
        Wrapper for `apt_pkg` module for running with Python 2.5
        '''
        try:
            result = apt_pkg.config.find_file(filespec)
        except AttributeError:
            result = apt_pkg.Config.FindFile(filespec)
        return result
    @staticmethod
    def _apt_cfg_dir(dirspec):
        '''
        Wrapper for `apt_pkg` module for running with Python 2.5
        '''
        try:
            result = apt_pkg.config.find_dir(dirspec)
        except AttributeError:
            result = apt_pkg.Config.FindDir(dirspec)
        return result
    def load(self, file):
        group = []
        f = open(file, 'r')
        for n, line in enumerate(f):
            valid, enabled, source, comment = self._parse(line)
            group.append((n, valid, enabled, source, comment))
        self.files[file] = group
    def save(self):