test/uname(): always lowercase

test/functional/ui/embed_spec.lua

@@ -49,7 +49,7 @@ local function test_embed(ext_linegrid)
   end)
 
   it("doesn't erase output when setting color scheme", function()
-    if 'openbsd' == string.lower(helpers.uname()) then
+    if 'openbsd' == helpers.uname() then
       pending('FIXME #10804', function() end)
       return
     end