Update test error text for Rust 1.54

Author: shepmaster

tests/spec/features/editions_spec.rb

@@ -24,7 +24,7 @@
     click_on("Run")
 
     within(:output, :stderr) do
-      expect(page).to have_content "thread 'main' panicked at 'Box<Any>'"
+      expect(page).to have_content "thread 'main' panicked at 'Box<dyn Any>'"
     end
   end
 

tests/spec/features/highlighting_error_output_spec.rb

@@ -10,7 +10,7 @@
 
   scenario "errors are highlighted" do
     within(:output, :stderr) do
-      expect(page).to have_css '.error', text: '1 type argument but 2 type arguments were supplied'
+      expect(page).to have_css '.error', text: '1 generic argument but 2 generic arguments were supplied'
       expect(page).to have_css '.error', text: 'aborting due to 2 previous errors'
       expect(page).to have_css '.error', text: /Could not compile `playground`/i
     end