Configure renovate to automatically open pull requests for docker image updates

Hopefully, this makes it run faster and prevents potential false-positives.

Although.. a false-positive is unlikely anyway.

Update borgmatic 1.8.2 -> 1.8.3

Update mautrix-discord 0.6.2 -> 0.6.3

Update mautrix-gmessages 0.2.0 -> 0.2.1

Update prometheus 2.47.1 -> 2.47.2

Update mautrix-whatsapp 0.10.2 -> 0.10.3

migrate prometheus exporter roles

update grafana 10.1.4 -> 10.1.5

Update Admin-API link

the old one is deprecated (says the page at the link target), and refers to this new one.

Warning Borg users before upgrading to Postgres 16

no postgres 16 support with borg, 15 works.

Update synapse v1.93.0 -> v1.94.0

Self-build now requires the new docker buildx/buildkit, so switch
from the ansible docker module to running a docker build command,
like elsewhere.

This adds a custom regex manager so dependencies in yml files can be found.

Without explicitly passing the `media_url` configuration,
Heisenbridge would try to guess it. It works most of the time,
but some people are experiencing trouble with it.

There's no need for wasteful work and for potential unreliability,
so we now configure the `media_url` explicitly.

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/2932

Update prometheus 2.47.0 -> 2.47.1

Document how to enable Draupnir report polling

Fix link in Draupnir docs

Patch contributed by JulianF.