Upgrade to Puppet Forge API version 3

Now that [we're using Puppet 3.6][puppet-3.6], we should be using version 3 of the Puppet Forge API[1][2].

To do this, upgrade librarian-puppet using:

```sh
bundle update librarian-puppet
```

`libarian-puppet`, as of version 1.1.0[3] can support the new API[4]. Also changes the URL in `Puppetfile` and `Puppetfile.lock` to use the new API.

As a side benefit this provides transport layer security (HTTPS) for the API connection, which gives us some guarantee that we are connecting to the correct server.

The line `LIBRARIAN_PUPPET_USE_V1_API: '1'` was added when I ran `bundle exec librarian-puppet install`. I can set it to false by running:

```sh
bundle exec librarian-puppet install --no-use-v1-api
```

`--use-v1-api` is the default[5][6] but libarian-puppet ignores this setting for the official Puppet Forge[7] and uses the v3 API. So leave it as-is to make running `librarian-puppet install` simpler.

[puppet-3.6]: abf2511

[1]: https://tickets.puppetlabs.com/browse/PUP-2093
[2]: https://docs.puppetlabs.com/puppet/3.6/reference/release_notes.html#module-tool-changes
[3]: https://github.com/rodjek/librarian-puppet/blob/a028cc5189d788762f68fd961a569a4b4fc16a61/Changelog.md#110
[4]: rodjek/librarian-puppet@f7b5997
[5]: https://github.com/rodjek/librarian-puppet/tree/2f0423e883b374ff805500acf1ab9986f2690e1d#how-to-use
[6]: https://github.com/rodjek/librarian-puppet/blob/2f0423e883b374ff805500acf1ab9986f2690e1d/lib/librarian/puppet/cli.rb#L64
[7]: https://github.com/rodjek/librarian-puppet/blob/2f0423e883b374ff805500acf1ab9986f2690e1d/lib/librarian/puppet/source/forge.rb#L154