An ambiguous bang like `!!d` raises an exception in function get_bang_url().  A
bang is only unique when the bang_definition from get_bang_definition_and_ac() is
a string / for a ambiguous bang the returned bang_definition is a dictionary.

Reported-by: user prg at #searxng:matrix.org on 2022/01/11
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

Bangs with a `*` suffix (e.g. `!!d*`) overwrite Bangs with the same
prefix (e.g. `!!d`) [1].  This can be avoid when a non printable character is
used to tag a LEAF_KEY.

[1] searxng#740 (comment)

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

Updated external bangs by::

    ./manage pyenv.cmd ./searxng_extra/update/update_external_bangs.py

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>