Use windows-2022 until issue #3255 is fixed

Use windows-2022 instead of windows-latest until
https://github.com/AOMediaCodec/libavif/issues/3255 is fixed.

windows-latest points to windows-2025 right now, which is being updated
to Visual Studio 2026. Visual Studio 2026 version >= 19.50 has an AVX2
intrinsics inlining bug, described at
https://gitlab.com/AOMediaCodec/SVT-AV1/-/work_items/2322#note_3455144085.

.github/workflows/ci-windows-installed.yml

diff --git a/.github/workflows/ci-windows-installed.yml b/.github/workflows/ci-windows-installed.yml
index 955e795..1c25acd 100644
--- a/.github/workflows/ci-windows-installed.yml
+++ b/.github/workflows/ci-windows-installed.yml
@@ -16,7 +16,9 @@
 
 jobs:
   build-windows-installed:
-    runs-on: windows-latest
+    # Use windows-2022 instead of windows-latest until
+    # https://github.com/AOMediaCodec/libavif/issues/3255 is fixed.
+    runs-on: windows-2022
     strategy:
       fail-fast: false
       matrix: