Merge topic 'release-CMP0115' into release

86b1c9de Fixed cmake 3.20rc3 CMP0115 warning

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: Ben Boeckel <ben.boeckel@kitware.com>
Merge-request: !7729

Rendering/GL2PSOpenGL2/Testing/Cxx/CMakeLists.txt

@@ -14,6 +14,6 @@ vtk_add_gl2ps_test_cxx(${GL2PSTests})
 
 # Compile the PNGCompare test, which is used to validate PNG images (read from
 # disk, not generated in VTK).
-list(APPEND tests PNGCompare)
+list(APPEND tests PNGCompare.cxx)
 
 vtk_test_cxx_executable(vtkRenderingGL2PSOpenGL2CxxTests tests RENDERING_FACTORY)