CI: don't use deprecated Windows-2019 image

PiperOrigin-RevId: 770024005

.github/workflows/build_test.yml

diff --git a/.github/workflows/build_test.yml b/.github/workflows/build_test.yml
index f089ddc..f1be1f3 100644
--- a/.github/workflows/build_test.yml
+++ b/.github/workflows/build_test.yml
@@ -106,7 +106,7 @@
             python_version: "3.10"
             # TODO: investigate why win-builds can't run tests
             py_setuptools_cmd: build_ext
-            os: windows-2019
+            os: windows-2022
 
           - name: maven
             build_system: maven