Updating:

- nixos module to use the new `account_reg.json` file.
- use nixpkgs pebble for integration tests.

Co-authored-by: Florian Klink <flokli@flokli.de>

Replace certbot-embedded pebble

Let's encrypt bumped ACME to V2. We need to update our nixos test to
be compatible with this new protocol version.

We decided to drop the Boulder ACME server in favor of the more
integration test friendly Pebble.

- overriding cacert not necessary
- this avoids rebuilding lots of packages needlessly
- nixos/tests/acme: use pebble's ca for client tests
- pebble always generates its own ca which has to be fetched

TODO: write proper commit msg :)

We build HandBrake with a newer ffmpeg than upstream expects,
triggering a problem where the audio samplerate defaults to zero
because HandBrake was not explicitly setting it.

This has been fixed in HandBrake upstream, but we must cherry pick
this change in order to produce videos with audio until HandBrake
1.3.0 is released.

Semi-automatic update generated by
https://github.com/ryantm/nixpkgs-update tools. This update was made
based on information from
https://repology.org/metapackage/mkvtoolnix/versions

Fixes #71311

* micronaut: 1.2.3 -> 1.2.5

Semi-automatic update generated by
https://github.com/ryantm/nixpkgs-update tools. This update was made
based on information from
https://repology.org/metapackage/micronaut/versions

* micronaut: keep description short

and run pre+post hooks when overriding install phase

simp_le: 0.9.0 -> 0.16.0

arion: init at 0.1.0.0

handbrake: fix missing audio