ci: switch to windows-2019

Related: actions/checkout#1186

Author: elopez

.github/workflows/ci.yml

@@ -18,7 +18,7 @@ jobs:
     needs: [lint, test]
     strategy:
       matrix:
-        environment: [ubuntu-latest, macos-latest, windows-latest]
+        environment: [ubuntu-latest, macos-latest, windows-2019]
 
     runs-on: ${{ matrix.environment }}
     steps:
@@ -89,7 +89,7 @@ jobs:
   test:
     strategy:
       matrix:
-        environment: [ubuntu-latest, macos-latest, windows-latest]
+        environment: [ubuntu-latest, macos-latest, windows-2019]
 
     runs-on: ${{ matrix.environment }}