Adjust MSYS2 workflow timeout (was slightly too short)

Author: ddeclerck

.github/workflows/windows-msys2.yml

@@ -71,7 +71,7 @@ jobs:
   build:
     needs: prepare
     runs-on: windows-latest
-    timeout-minutes: 15
+    timeout-minutes: 20
     strategy:
       fail-fast: false
       matrix: