`<yvals_core.h>`: Update `_MSVC_STL_UPDATE` to December 2025

[StephanTLavavej]

Explanation on our wiki: Macro _MSVC_STL_UPDATE

Code:

STL/stl/inc/yvals_core.h

Line 925 in c370e05

#define _MSVC_STL_UPDATE 202511L

Previous issue: #5821

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