Fix Windows CI: pin to windows-2022 (VS2022 toolset) (#192)

## Problem

Every Windows/UWP build is failing. GitHub repointed the
`windows-latest` label to a **VS2026** toolset (internal image
`windows-2025-vs2026`). Its newer MSVC emits **C4875** (`a non-string
literal argument to [[gsl::suppress]] is deprecated`) from inside the
GSL headers we pull transitively via `arcana.cpp`, and our `/WX` builds
promote it to a hard error.

## Fix

Pin the Win32 and UWP jobs to the **windows-2022** runner, which still
provides the established VS2022 toolset that doesn't emit C4875. This
restores green CI with no source or dependency-graph change, and matches
the approach taken in BabylonNative (BabylonJS/BabylonNative#1742).

(Originally proposed as a GSL v4.2.2 bump / `/wd4875` suppression — see
the closed #191 — but pinning the runner is the smaller, decoupled fix
and keeps us on the known-good toolchain.)

## Validation

CI on this branch confirms the Win32/UWP builds are green again on
windows-2022.

Co-authored-by: Branimir Karadžić <branimirk@microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: 3 people

.github/workflows/build-uwp.yml

@@ -12,7 +12,7 @@ on:
 
 jobs:
   build:
-    runs-on: windows-latest
+    runs-on: windows-2022
     timeout-minutes: 15
     steps:
       - uses: actions/checkout@v5

.github/workflows/build-win32.yml

@@ -12,7 +12,7 @@ on:
 
 jobs:
   build:
-    runs-on: windows-latest
+    runs-on: windows-2022
     timeout-minutes: 15
     steps:
       - uses: actions/checkout@v5