ci: use win 2019 for code cov

Author: piksel

.github/workflows/build-test.yml

@@ -76,7 +76,7 @@ jobs:
 
   CodeCov:
     name: Code Coverage
-    runs-on: windows-latest
+    runs-on: windows-2019
     env:
       DOTCOVER_VER: 2021.1.2
       DOTCOVER_PKG: jetbrains.dotcover.commandlinetools