Slightly simplify running the GUI tests in the Mac CI workflow

No real changes, just don't use pipefail option when we're not using
pipelines at all -- this was somewhat confusing.

.github/workflows/ci_mac.yml

@@ -206,8 +206,7 @@ jobs:
         export ASAN_OPTIONS=fast_unwind_on_malloc=0
         # Exclude tests that are currently known to fail
         wx_tests_selection='~[valnum] ~wxPersistTLW ~wxPersistDVC ~wxTopLevel::Show ~wxFont::Weight ~wxFont::NativeFontInfo ~WebView ~RadioButton::Single ~RadioButton::Focus ~wxHtmlPrintout::Pagination ~ChoiceTestCase ~ComboBoxTestCase ~CheckListBoxTestCase ~ListBoxTestCase ~RearrangeListTestCase ~wxTextCtrl::GetBestSize ~TextCtrlTestCase ~ClippingBoxTestCase::wxClientDC ~wxExecute::RedirectUTF8 ~Ellipsization::NormalCase ~SpinCtrl::* ~SpinCtrlDouble::* ~NotebookTestCase ~SettingsTestCase ~XRC::LoadURL ~Window::Show ~Window::SizerErrors ~ModalDialogsTestCase ~Button::Click ~Button::Disabled ~wxDVC::GetItemRect ~wxDVC::AppendTextColumn ~Grid::KeyboardSelection ~Grid::CellClick ~Grid::ReorderedColumnsCellClick ~Grid::CellSelect ~wxStyledTextCtrl::AutoComp ~EvtLoopTestCase ~EventPropagationTestCase'
-        # Explicitly use bash because /bin/sh doesn't have pipefail option
-        /bin/bash -o pipefail -c "./test_gui $wx_tests_selection"
+        ./test_gui $wx_tests_selection
 
     - name: Building samples
       if: matrix.skip_testing != true && matrix.skip_samples != true