[drop] Acgsou engine - www.acgsou.com no longer exists

- https://www.acgsou.com/ acgsou.com is redirected to 36dm.club
- @rinpatch do not plan on maintaining the engine [1]

[1] https://github.com/searx/searx/pull/1283#issuecomment-798783585



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