[workflow] Pin windows-2022 to try to fix flaky python errors

Just throwing stuff at the wall to see if maybe this time it fixes intermittent
errors about python.exe missing on Windows.

Author: mshroyer

.github/workflows/ci.yml

@@ -21,7 +21,7 @@ jobs:
             toolchain: beta
           - os: ubuntu-latest
             toolchain: nightly
-          - os: windows-latest
+          - os: windows-2022
             toolchain: stable
           - os: macos-latest
             toolchain: stable