Server: version bump for httplib and json

[ngxson]

• Update httplib to 0.15.3
• Update json to 3.11.3

Closes #6162

[slaren]

Build is failing due to an unused parameter in a 3rd party library. Coincidentally, after finding 188 instances of GGML_UNUSED in ggml-cuda.cu, I was about to suggest to remove this warning entirely, because IMO it causes more harm than good to the code quality.

 examples/server/httplib.h:4797:45: error: unused parameter ‘content_length’ [-Werror=unused-parameter]

[ngxson]

Yeah I got the same error on local build, seems like because the parameter is only being used by assert(), which is not present in our build. At first, I didn't want to modify the code because I didn't want to touch an external code. But if that breaks the CI, we have no choice then.

[phymbert]

Note the windows server tests is failing for something not related. I will fix it later on

[phymbert]

Note the windows server tests is failing for something not related. I will fix it later on

@ngxson Tests have been:

• broken in: common : disable repeat penalties by default #6127
• fixed in: server tests : more pythonic process management; fix bare except: #6146

Please merge master into this to be sure all is OK on server tests, then I am happy to merge this important upstream security upgrade

[ggerganov]

The change in e5ed307 does not work in Debug builds. Use (void)(content_length);

We can alternatively do as proposed by @slaren - disable the warning and eventually get rid of the unused calls

[ngxson]

I added (void)(content_length); because it seems to be the most non-destructive choice for now.

I also merged latest master to pick up the changes that @phymbert mentioned, hopefully the CI will pass