chore(3p/sources): Bump channels & overlays

Use nixos-unstable-small which fixes CVE-2018-25032
(out of bounds write while compressing).

* //users/grfn/xanthous:

  - Supporting random-fu 0.3 requires considerable changes and patching
    random-extras (https://github.com/aristidb/random-extras/pull/5).

    For now we downgrade random-fu and its dependency rvar to 0.2.*,
    forcing us to build xanthous with GHC 8.10.7, due to random-fu 0.2.*
    not supporting that version.

    Nix expressions for the downgraded packages are checked in to avoid
    the potential need to compile Haskell at pipeline eval time.

  - generic-arbitrary exposes a GenericArbitrary newtype now.
    This means we no longer have to implement it in xanthous
    downstream and patch generic-arbitrary to expose the
    GArbitrary type class.

  - Minor adjustments for lens 5.0:

    Xanthous.Game.Memo: clear needs to use ASetter' instead of Lens'

    Xanthous.Data.EntityMap: TraversableWithIndex no longer has an
    itraversed function.

  - Xanthous.Orphans: adjust for aeson's KeyMap, use KM.size explicitly
    instead of relying on MonoTraversable's length

* //nix/buildLisp: the CCL issue has resurfaced, disabling the
  implementation once again.

* //3p/arion: remove, as depot uses the nixpkgs package of it anyways.

* //users/wpcarro: accomodate GHC 9.0.1's stricter parsing of operators.

* //users/tazjin: disable rustfmt as it stopped respecting settings

* //3p/overlays: upgrade home-manager until fix for serivce generation
  has landed upstream

* //users/grfn/system: remove rr override, as the pinned commit is part
  of the 5.5.0 release shipped by nixpkgs.

Change-Id: If229e7317ba48498f85170b57ee9053f6997ff8a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5428
Tested-by: BuildkiteCI
Autosubmit: sterni <sternenseemann@systemli.org>
Reviewed-by: grfn <grfn@gws.fyi>
Reviewed-by: tazjin <tazjin@tvl.su>
Reviewed-by: wpcarro <wpcarro@gmail.com>

users/wpcarro/zoo/Main.hs

@@ -157,4 +157,4 @@ parseInput x =
     _ -> Nothing
 
 main :: IO ()
-main = Warp.run 8000 $ serve (Proxy @ Api) server
+main = Warp.run 8000 $ serve (Proxy @Api) server