[c++] update to fmt 11.1.2, fast_double_parser 0.8.0

[jameslamb]

Contributes to #3763.
Contributes to #5691.

Proposes updated the projects vendored in here as git submodules to their latest versions:

• boostorg/compute: being worked on separately in [ci] update libboost version from 1.74 to 1.83 #6582
• fmtlib/fmt: from v10.1.1 (August 2023) to v11.1.2 (January 2025)
  • why not the latest, 11.1.3? see [c++] update to fmt 11.1.2, fast_double_parser 0.8.0 #6802 (comment)
• lemire/fast_double_parser: from v0.7.0 (December 2022) to v0.8.0 (May 2024)
• libeigen/eigen: no change (already on v3.4.0, August 2021)

How I did that

# fast_double_parser
cd ./external_libs/fast_double_parser
git fetch origin --tags
git checkout v0.8.0
cd ../../

# fmt
cd ./external_libs/fmt
git fetch origin 11.1.2
git checkout 11.1.2
cd ../../

# commit update
git add ./external_libs

Benefits of this change

Pulls in bugfixes, security patches, performance improvements.

The last update like this was #6074, over a year ago.

[jameslamb]

The only compilation failure left is this one on Appveyor:

c:\projects\lightgbm\lightgbm-python\external_libs\fmt\include\fmt\base.h(743): error C2338: (compiling source file
C:\projects\lightgbm\lightgbm-python\src\io\tree.cpp) [C:\Users\appveyor\tmp\tmpaktrbpjy\build\lightgbm_objs.vcxproj]
c:\projects\lightgbm\lightgbm-python\external_libs\fmt\include\fmt\base.h(743): error C2327:
'fmt::v11::basic_specs::data_': is not a type name, static, or enumerator (compiling source file
C:\projects\lightgbm\lightgbm-python\src\metric\dcg_calculator.cpp

(build link)

That code was JUST introduced into fmt 2 weeks ago: fmtlib/fmt@01914f0

Note that that is failing with MSVC 2015... other builds with later MSVC versions do not have this compilation error, for example this one with Visual Studio 2019: https://github.com/microsoft/LightGBM/actions/runs/12981353281/job/36199682684?pr=6802

I'm going to try rolling back one minor version to fmt 11.1.2 to see if that's enough to avoid it. Then maybe separately try to file a bug report with fmt and see if they'd be willing to support such an old version of MSVC.

[jameslamb]

/gha run r-valgrind

[StrikerRUS]

LGTM, thanks for doing this!