<!--- Verify first that your issue is not already reported on GitHub -->
<!--- Also test if the latest release and devel branch are affected too -->
<!--- Complete *all* sections as described, this form is processed automatically -->

##### SUMMARY
<!--- Explain the problem briefly below -->
We publish semver collection (vyos.vyos:0.0.1-dev58) to ansible galaxy, however by default it seems ansible-galaxy client will not be able to find it. You must specific the version number directly to fetch it.

https://galaxy.ansible.com/vyos/vyos


EDIT:

This is working as expect, but it would be nice to Include:

   --pre                       Include pre-release and development versions. By default, ansible-galaxy only finds stable versions.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
ansible-galaxy

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
ansible 2.9.1
```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below

```


##### STEPS TO REPRODUCE
<!--- Describe exactly how to reproduce the problem, using a minimal test-case -->

<!--- Paste example playbooks or commands between quotes below -->
```yaml
$ ansible-galaxy collection install vyos.vyos -p /tmp/11123
[WARNING]: The specified collections path '/tmp/11123' is not part of the configured Ansible collections paths '/home/pabelanger/.ansible/collections:/usr/share/ansible/collections'. The
installed collection won't be picked up in an Ansible run.

Process install dependency map
ERROR! Cannot meet requirement * for dependency vyos.vyos from source 'https://galaxy.ansible.com/api/'. Available versions before last requirement added: 
Requirements from:
	base - 'vyos.vyos:*'
(venv) [pabelanger@localhost openstack]$ ansible-galaxy collection install vyos.vyos:0.0.1-dev57 -p /tmp/11123
[WARNING]: The specified collections path '/tmp/11123' is not part of the configured Ansible collections paths '/home/pabelanger/.ansible/collections:/usr/share/ansible/collections'. The
installed collection won't be picked up in an Ansible run.

Process install dependency map
Starting collection install process
Installing 'vyos.vyos:0.0.1-dev57' to '/tmp/11123/ansible_collections/vyos/vyos'
```

<!--- HINT: You can paste gist.github.com links for larger files -->

##### EXPECTED RESULTS
<!--- Describe what you expected to happen when running the steps above -->
vyos.vyos collection to be found and installed

##### ACTUAL RESULTS
<!--- Describe what actually happened. If possible run with extra verbosity (-vvvv) -->

<!--- Paste verbatim command output between quotes -->
```paste below

```

display.display("Installing '%s:%s' to '%s'" % (to_text(self), self.latest_version, collection_path))
        if self.b_path is None:
            download_url = self._metadata.download_url
            artifact_hash = self._metadata.artifact_sha256
            headers = {}
            self.api._add_auth_token(headers, download_url, required=False)
            self.b_path = _download_file(download_url, b_temp_path, artifact_hash, self.api.validate_certs,
                                         headers=headers)
        if os.path.exists(b_collection_path):
            shutil.rmtree(b_collection_path)
        os.makedirs(b_collection_path)
        with tarfile.open(self.b_path, mode='r') as collection_tar:
            files_member_obj = collection_tar.getmember('FILES.json')
            with _tarfile_extract(collection_tar, files_member_obj) as files_obj:
                files = json.loads(to_text(files_obj.read(), errors='surrogate_or_strict'))
            _extract_tar_file(collection_tar, 'MANIFEST.json', b_collection_path, b_temp_path)
            _extract_tar_file(collection_tar, 'FILES.json', b_collection_path, b_temp_path)
            for file_info in files['files']:
                file_name = file_info['name']
                if file_name == '.':
                    continue
                if file_info['ftype'] == 'file':
                    _extract_tar_file(collection_tar, file_name, b_collection_path, b_temp_path,
                                      expected_hash=file_info['chksum_sha256'])
                else:
                    os.makedirs(os.path.join(b_collection_path, to_bytes(file_name, errors='surrogate_or_strict')))
    def set_latest_version(self):
        self.versions = set([self.latest_version])
        self._get_metadata()
    def verify(self, remote_collection, path, b_temp_tar_path):