fixed missing whitespace in plan() debug logging

When debug logging is enabled, the plan() function logs lines like:

    <previous output>
    Plan: DEBUG: __init__: Creates=13, Updates=0, Deletes=0Existing=0
    <following output>

  Where a space between "Deletes=0" and "Existing=0" is missing.
  This adds it.

pools used as fallbacks should count as seen

Change DNSimple's Provider to query zones instead domains

A quick summary of a problem with have with DNSimple provider:
Let's suppose that I have the following config:

zones:
  30.114.195.in-addr.arpa.:
    sources:
      - config
    targets:
      - dnsimple

Even if a customer has this Reverse zone configured in DNSimple, this
fails with:

400 Bad Request for url: https://api.sandbox.dnsimple.com/v2/x/domains

because it is trying to create a domain because the zone wasn't found.
octodns.provider.dnsimple.DnsimpleClientNotFound: Not found

This happens because the GET /domains endpoint at DNSimple does not
bring Reverse Zones. To make this work nice, we should use /zones/
instead making it return properly the reverse zones.

- implemented HetznerClient API class
- tested manually, lacking formal tests

Capture plan output in File as argument to sync

Co-authored-by: Ross McFarland <ross@github.com>

Co-authored-by: Ross McFarland <ross@github.com>

Change the auth value to have a proper string not a binary rep

Enable NS support for non-root NS records

Bump pyyaml from 5.3.1 to 5.4

Bumps [pyyaml](https://github.com/yaml/pyyaml) from 5.3.1 to 5.4.
- [Release notes](https://github.com/yaml/pyyaml/releases)
- [Changelog](https://github.com/yaml/pyyaml/blob/master/CHANGES)
- [Commits](https://github.com/yaml/pyyaml/compare/5.3.1...5.4)

Signed-off-by: dependabot[bot] <support@github.com>

Update README.md: fix typo