1.5.4rc1

This is the first release candidate for the 1.5.4 stable release of ara.

Changes since 1.5.3:

CLI
---

New commands were added to the 'ara' CLI:

- ara playbook metrics: provides stats aggregated by name, path, ansible version or controller
- ara host metrics: provides task result stats for hosts across playbooks
- ara task metrics: provides duration stats aggregated by task name, action/module or path

Refer to the documentation for examples and more information on these commands:
https://ara.readthedocs.io/en/latest/cli.html

Callback plugin
---------------

- Threading is now disabled by default to avoid running into sqlite locking contention
  For details, see: https://github.com/ansible-community/ara/issues/195
- The callback didn't provide a timezone for timestamps which could result in a wrong
  interpretation by the API server. Timestamps are now provided as UTC.

Controller hostname
-------------------

The hostname of the controller that ran the playbook is now recorded by ara.

Playbooks can be filtered by controller in the UI as well as the API:

    /api/v1/playbooks?controller=localhost

As well as with the CLI, for example:

    ara playbook list --controller=localhost
    ara playbook metrics --controller=localhost

Container images
----------------

- ARA API server container images are now published to quay.io/recordsansible/ara-api
  in addition to hub.docker.com/r/recordsansible/ara-api.
- Fedora 32 images were replaced by images based on Fedora 33
- The 'which' package is now installed as a dependency
- Removed a temporary workaround for dynaconf switching from PyYAML to ruamel.yaml

UI
--

- Added missing information about the play when browsing details for a task result

Upgrade notes
-------------

The new controller hostname feature introduces a SQL migration to update the database schema.
After upgrading, database migrations will need to be run at least once using 'ara-manage migrate'.

Because the hostname was not previously saved and can't be recovered retroactively,
playbooks that were recorded before the upgrade will have the controller set to 'localhost'.
This tag has no release notes.