Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/1062

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/1062

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1057

Not sure if this is beneficial though.

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1057

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/1058

We may try to capture such calls and return a friendlier response (HTML
or JSON) saying "The Synapse Admin API is not enabled", but that may not
be desirable.

For now, we stick to what "upstream" recommends: "simply
don't proxy these APIs", which should lead to the same kind of 404 that
we have now.
See here: 6660912226/docs/reverse_proxy.md (synapse-administration-endpoints)

Related to https://github.com/devture/exim-relay/pull/9

Related to https://github.com/Awesome-Technologies/synapse-admin/issues/132

We should switch back when >0.8.0 gets released.

This release fixes a denial of service attack (CVE-2021-29471) against Synapse's push rules implementation. Server admins are encouraged to upgrade.

Ref: https://github.com/matrix-org/synapse/releases/tag/v1.33.2

689dcea773 wasn't enough. The `upstream/..` tags are
just upstream sources, without the alpine-based Dockerfile.
We need to use the `docker/..` tags for that (or `master`)

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/1032

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/1023

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1009

Related to https://github.com/devture/exim-relay/issues/6

Related to https://github.com/Awesome-Technologies/synapse-admin/issues/132

Co-authored-by: Aaron Raimist <aaron@raim.ist>

Jitsi-meet enabled websockets by default, claiming better reliability.
Matrix-nginx-proxy configuration has been set up according to the
Prosody documentation: https://prosody.im/doc/websocket

Changelog:
https://github.com/jitsi/docker-jitsi-meet/blob/stable-5765-1/CHANGELOG.md

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/1023

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1009

Potentially fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/1022

**HSTS Preloading:**
In its strongest and recommended form, the [HSTS policy](https://www.chromium.org/hsts) includes all subdomains, and indicates a willingness to be “preloaded” into browsers:
`Strict-Transport-Security: max-age=31536000; includeSubDomains; preload`

**X-Xss-Protection:**
`1; mode=block` which tells the browser to block the response if it detects an attack rather than sanitising the script.

More Production ready nginx headers for Matrix client element.