* Implement MSC 1929 Homeserver Admin Contact
Fixes #1612

For details to the proposed (not accepted yet) MSC, see:
https://github.com/matrix-org/matrix-spec-proposals/blob/hs/proposal-admin-contact-1/proposals/1929-admin-contact.md

* Implement feedback from PR #1931

* Implement feedback from PR #1931

* Fix mixed indentation

add ansible-lint; cleanup yamllint

update redis 6.2.6 -> 7.0.3

update sygnal 0.11.0 -> 0.12.0

update prometheus 2.36.2 -> 2.37.0

update nginx 1.21.6 -> 1.23.0

update grafana 9.0.2 -> 9.0.3

update dynamic dns 3.9.1-ls89 -> 3.9.1-ls92

update hydrogen 0.2.29 -> 0.2.33; sync config

fix mautrix-whatsapp config

add/unify 'Project source code URL' link across all roles

update buscarron from github -> gitlab

Update mautrix whatsapp 0.5.0 -> 0.6.0

project doesn't exist on github anymore

Update recommended Skype bridge in docs

Improvement over e4caf3fa81.

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1921

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1921

signald: 0.18.5 -> 0.20.0

Bump frenck/action-yamllint from 1.1.2 to 1.2.0

Bumps [frenck/action-yamllint](https://github.com/frenck/action-yamllint) from 1.1.2 to 1.2.0.
- [Release notes](https://github.com/frenck/action-yamllint/releases)
- [Commits](https://github.com/frenck/action-yamllint/compare/v1.1.2...v1.2.0)

---
updated-dependencies:
- dependency-name: frenck/action-yamllint
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Unrelated to the original branch I added the matrix-registration bot as it was missing in the readme