Plugin: Update httplib to 0.15.3 / openssl to 3.3.0

[hbeni]

Upgrade httplib and openssl for the updater

Possibly obsoleted by #147

[hbeni]

Currently fails with CodeQL for httplib:

2024-05-14T05:25:38.5701105Z In file included from ./lib/updater.cpp:55,
2024-05-14T05:25:38.5703331Z                  from fgcom-mumble.cpp:1148:
2024-05-14T05:25:38.5721865Z ./lib/http/httplib.h: In member function ‘bool httplib::detail::mmap::open(const char*)’:
2024-05-14T05:25:38.5723953Z ./lib/http/httplib.h:2696:14: error: ‘::CreateFile2’ has not been declared; did you mean ‘CreateFileW’?
2024-05-14T05:25:38.5725234Z  2696 |   hFile_ = ::CreateFile2(wpath.c_str(), GENERIC_READ, FILE_SHARE_READ,
2024-05-14T05:25:38.5726015Z       |              ^~~~~~~~~~~
2024-05-14T05:25:38.5729316Z       |              CreateFileW
2024-05-14T05:26:01.1985213Z make[1]: *** [Makefile:110: plugin-win64-only] Error 1
2024-05-14T05:26:01.1986021Z make[1]: Leaving directory '/home/runner/work/fgcom-mumble/fgcom-mumble/client/mumble-plugin'
2024-05-14T05:26:01.1987951Z make: *** [Makefile:223: plugin-win64] Error 2
2024-05-14T05:26:01.2000806Z ##[error]Process completed with exit code 2.
``