Change trunk windows version to 2019 from latest

Author: Greenscreen23

.github/workflows/ci-trunk.yml

@@ -17,7 +17,7 @@ jobs:
       fail-fast: false
       matrix:
         # Select platform(s)
-        os: [ ubuntu-latest, macos-latest, windows-latest ]
+        os: [ ubuntu-latest, macos-latest, windows-2018 ]
         # Select compatible Smalltalk image(s)
         smalltalk: [ Squeak64-trunk]
     name: ${{ matrix.smalltalk }} on ${{ matrix.os }}