Add `/std:c++latest` to VC option in `build.yml`.
MODIFY
.github/workflows/build.yml
.github/workflows/build.yml
@@ -125,4 +125,4 @@ jobs:
MRUBY_TARGET: appveyor
# TODO(take-cheeze): Re-enable /O2
CFLAGS: "/c /nologo /W3 /we4013 /Zi /MD /D_CRT_SECURE_NO_WARNINGS"
- CXXFLAGS: "/c /nologo /W3 /Zi /MD /EHs /D_CRT_SECURE_NO_WARNINGS"
+ CXXFLAGS: "/c /nologo /W3 /Zi /MD /EHs /D_CRT_SECURE_NO_WARNINGS /std:c++latest"

Add `/std:c++latest` to VC option in `build.yml`.