Update cxxopts to v3.3.1 (GCC-15 compatibility)

[bekard]

When I was building it with g++-15 and got an error:

In file included from /home/ant/prog/temp/ctranslate/CTranslate2/cli/translator.cc:4:
/home/ant/prog/temp/ctranslate/CTranslate2/cli/../third_party/cxxopts/include/cxxopts.hpp:85:5: error: ‘uint8_t’ does not name a type
   85 |     uint8_t major, minor, patch;

it's because

GCC-15 no longer includes implicitly.
https://gcc.gnu.org/gcc-15/porting_to.html

PR with fix in cxxopts: jarro2783/cxxopts#438

[bekard]

Failed check looks unrelated to PR's changes. Please restart the failed job.

[jordimas]

Thanks so much!