### 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
for filename, sources in list(self.files.items()):
            if sources:
                d, fn = os.path.split(filename)
                try:
                    os.makedirs(d)
                except OSError as ex:
                    if not os.path.isdir(d):
                        self.module.fail_json("Failed to create directory %s: %s" % (d, to_native(ex)))
                try:
                    fd, tmp_path = tempfile.mkstemp(prefix=".%s-" % fn, dir=d)
                except (OSError, IOError) as e:
                    self.module.fail_json(msg='Unable to create temp file at "%s" for apt source: %s' % (d, to_native(e)))
                f = os.fdopen(fd, 'w')
                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')
                    line = ''.join(chunks)
                    try: