[pegtl] Update to 3.2.6 for MSVC and GCC fixes

[wravery]

• What does your PR fix?

  Recent versions of MSVC and GCC changed the behavior of built-in macros and template parsing, which breaks the PEGTL demangle function when it's used in cppgraphlgen. This shows up as a build break in the cppgraphqlgen port. This version of PEGTL includes workarounds/updates to work with these compiler versions.

• Which triplets are supported/not supported? Have you updated the CI baseline?

  All, Yes (removing cppgraphqlgen failures on Windows).

• Does your PR follow the maintainer guide?

  Yes.

• If you have added/updated a port: Have you run ./vcpkg x-add-version --all and committed the result?

  Yes.

[wravery]

@BillyONeal I think this will unblock the cppgraphqlgen port with the latest CI baselines/VMs.

[BillyONeal]

OK, I pushed a commit to remove those from the baseline then. I didn't remove the Linux one since the comment there says it's about newer GCC needed rather than older.

[BillyONeal]

Thanks for such a quick fix!