[taocpp-json] Update to 1.0.0-beta.14

[kiwixz]

No releases are available yet, so I just picked the latest beta.

This notably fixes the following a GCC>=15 warning caused by tao/json/external/pegtl/demangle.hpp:7:

/usr/include/c++/15/ciso646:49:6: warning: #warning "<ciso646> is not a standard header since C++20, use <version> to detect implementation-specific macros" [-Wcpp]
   49 | #    warning "<ciso646> is not a standard header since C++20, use <version> to detect implementation-specific macros"
      |      ^~~~~~~

Followed advice from #27004 (comment) to include the new submodule, PEGTL was previously vendored.

Tested on Linux x64 with a small example.

• Changes comply with the maintainer guide.
• SHA512s are updated for each updated download.
• The "supports" clause reflects platforms that may be fixed by this new version, or no changes were necessary.
• Any fixed CI baseline and CI feature baseline entries are removed from that file, or no entries needed to be changed.
• All patch files in the port are applied and succeed.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Exactly one version is added in each modified versions file.

[BillyONeal]

This needs to not use a vendored copy of that library and use the one from https://github.com/microsoft/vcpkg/tree/master/ports/pegtl instead.

[BillyONeal]

Alternately, the port doesn't seem to install anything from here and it is header only; is this change needed at all?

[kiwixz]

I did look for PEGTL in vcpkg but not hard enough it seems, would have saved me some work!

The CMakeLists.txt of the json library tries to find_package PEGTL and otherwise add_subdirectory the submodule, so the dependency is needed (and probably a good idea anyway so it "just works").

[BillyONeal]

Thanks! (Will merge if build works out)