mingw - Revert changes; back to windows-2019 which doesn't run; at least we don't get a big red X.

Author: cboulay

.github/workflows/mingw_static.yml

@@ -56,7 +56,7 @@ jobs:
                 -Dlslgitrevision=${{ github.sha }} \
                 -Dlslgitbranch=${{ github.ref }} \
                 -DLSL_OPTIMIZATIONS=OFF \
-                -G Ninja
+                -G 'MSYS Makefiles'
 
     - name: make
       run: cmake --build build --target install --config Release -j --verbose