build(deps-dev): bump fakeredis from 2.20.1 to 2.21.0

Bumps [fakeredis](https://github.com/cunla/fakeredis-py) from 2.20.1 to 2.21.0.
- [Release notes](https://github.com/cunla/fakeredis-py/releases)
- [Commits](cunla/fakeredis-py@v2.20.1...v2.21.0)

---
updated-dependencies:
- dependency-name: fakeredis
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

api: fix set typo in request packages

Reported-by: Tianling Shen <cnsztl@immortalwrt.org>
Signed-off-by: Paul Spooren <mail@aparcar.org>

api: allow to prefix packages with a +

When adding a + to the beginning of a package name it will modify the
order of packages and thereby fix dependency issues of OPKG.

This is more of a advanced user feature.

Signed-off-by: Paul Spooren <mail@aparcar.org>

branches: add 22.03.2 and 21.02.5

Add new service releases.

Signed-off-by: Alex Taran <oleksii.taran@gmail.com>

add branch-off-revision for each stable branch

In order to be able which cross-branch package_changes to apply the clients needs to know at which point a stable branch has branched off the main/master branch.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

build: cleanup KDIR_TMP after each build

Clean the KDIR_TMP folder after each build since it stores every image
ever created.

Also run isort and black.

Signed-off-by: Paul Spooren <mail@aparcar.org>

asu: allow the usage of branches.yml

It's easier to write and understand. It's now possible to define a file
called `branches.yml` containing whatever branch information you'd like.

It's loaded from the config option BRANCHES_PATH if defined, if not the
internal branches.yml file is used.

To stay compatible with existing setups changes only happen if BRANCHES
wasn't previously defined, like it would be the case if still added in
the config.py

Signed-off-by: Paul Spooren <mail@aparcar.org>

build: correctly clean up outdated imagebuilders

Right not the stamp/sha25sums files stay since the wrong path for
deleting them is given. This results in jobs to fail and leftover files
which cause other jobs to fail.

Signed-off-by: Paul Spooren <mail@aparcar.org>

janitor: automatically refresh branches.json

For SNAPSHOTS the targets and architectures likely change over time.
Automatically create the overview file to lower manual maintenance.

Signed-off-by: Paul Spooren <mail@aparcar.org>

api: allow empty filesystem string

Clients may send an empty filesystem string, don't ignore their requests but
handle them as if no filesystem was set.

Signed-off-by: Paul Spooren <mail@aparcar.org>