Ensure python3-unicodedata2 is available in installer iso

Installation from the weekly installer image fails (2022-W40 and
2022-W41). From syslog:

    in-target: The following packages have unmet dependencies:
    in-target:  king-phisher : Depends: python3-matplotlib (>= 1.4.3) but it is not installable
    in-target:                 Recommends: python3-mpltoolkits.basemap (>= 1.0.7) but it is not installable

From a manual install, using the iso packages set in sources.list:

    # apt install king-phisher
    [...]
    The following packages have unmet dependencies:
     python3-fonttools : Depends: python3-unicodedata2 (>= 14.0.0) but it is not installable or
                                  python3-all (>= 3.11.0) but 3.10.6-1 is to be installed
    E: Unable to correct problems, you have held broken packages.

Dependency chain is as follow:

    king-phisher
    +-- python3-matplotlib
      +-- python3-fonttools
        +-- python3-unicodedata2 (>= 14.0.0) | python3-all (>= 3.11.0)

In the set of packages that are available in the iso, we don't have
python3-unicodedata2 , however we have python3-all , BUT it's at version
3.10.6-1 ... So nothing can satisfy the dependency.

For now, let's manually force python3-unicodedata2 in the iso, as a
workaround.

simple-cdd/profiles/offline.downloads

@@ -19,3 +19,6 @@ pipewire-pulse
 # Ensure speech-dispatcher recommends are available
 sound-icons
 speech-dispatcher-espeak-ng
+# Ensure python3-unicodedata2 is available. Can drop when
+# python3-all (>= 3.11.0) enters Kali rolling.
+python3-unicodedata2