ci: Revert to Windows-latest

It seems the issues with the Windows runners have been fixed by Github

Author: LeonMatthesKDAB

.github/workflows/build.yml

@@ -20,7 +20,7 @@ jobs:
       matrix:
         os:
           - ubuntu-latest
-          - windows-2019
+          - windows-latest
           - macos-latest
 
     steps: