<!--- 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

```

login_parser = parser.add_parser('login', parents=parents,
                                         help="Login to api.github.com server in order to use ansible-galaxy role sub "
                                              "command such as 'import', 'delete', 'publish', and 'setup'")
        login_parser.set_defaults(func=self.execute_login)
        login_parser.add_argument('--github-token', dest='token', default=None,
                                  help='Identify with github token rather than username and password.')
    def add_info_options(self, parser, parents=None):
        info_parser = parser.add_parser('info', parents=parents, help='View more details about a specific role.')
        info_parser.set_defaults(func=self.execute_info)
        info_parser.add_argument('args', nargs='+', help='role', metavar='role_name[,version]')
    def add_verify_options(self, parser, parents=None):
        galaxy_type = 'collection'
        verify_parser = parser.add_parser('verify', parents=parents, help='Compare checksums with the collection(s) '
                                          'found on the server and the installed copy. This does not verify dependencies.')
        verify_parser.set_defaults(func=self.execute_verify)
        verify_parser.add_argument('args', metavar='{0}_name'.format(galaxy_type), nargs='*', help='The collection(s) name or '
                                   'path/url to a tar.gz collection artifact. This is mutually exclusive with --requirements-file.')
        verify_parser.add_argument('-i', '--ignore-errors', dest='ignore_errors', action='store_true', default=False,
                                   help='Ignore errors during verification and continue with the next specified collection.')
        verify_parser.add_argument('-r', '--requirements-file', dest='requirements',
                                   help='A file containing a list of collections to be verified.')
    def add_install_options(self, parser, parents=None):