Build ElmerGUI with VTK in CI on Windows/MinGW.

Also install a couple of optional run-time dependencies that are needed
when building with VTK.

.github/workflows/build-windows-mingw.yaml

@@ -61,10 +61,14 @@ jobs:
             fc:p
             cmake:p
             msmpi:p
+            opencascade:p
             openblas:p
             parmetis:p
             qt6-declarative:p
             qwt-qt6:p
+            vtk:p
+            boost:p
+            cli11:p
             ${{ matrix.umfpack-package }}
 
       - name: install MSMPI
@@ -95,6 +99,7 @@ jobs:
             -DWITH_Mumps=OFF \
             -DWITH_ELMERGUI=ON \
             -DWITH_QT6=ON \
+            -DWITH_VTK=ON \
             -DWITH_PARAVIEW=ON \
             -DCREATE_PKGCONFIG_FILE=ON \
             ${{ matrix.umfpack-cmake-flags }} \