[fix] remove certifi from requirements.txt [1]
[1] https://github.com/searxng/searxng/commit/93f7f7eee2e8
forensics:
- Requirement certify was added in 35a2bc5650b
- Since commit 93f7f7eee certifi is no longer needed. Not sure why 93f7f7eee
upgraded certifi while removing the usage of this package from the source code
in the same commit.
Closes: https://github.com/searxng/searxng/pull/3182
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>