Remove duplicate line

Author: pfultz2

gui/test/resultstree/CMakeLists.txt

@@ -45,7 +45,6 @@ if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
     target_compile_options_safe(test-resultstree -Wno-suggest-attribute=noreturn)
 endif()
 
-
 if (REGISTER_GUI_TESTS)
     # TODO: might crash - see #13223
     #add_test(NAME test-resultstree COMMAND $<TARGET_FILE:test-resultstree> -platform offscreen)