exclude text nodes from counting in :has() selector

`descendants` function also includes text nodes,
which causes `name node` function to fail down the line,
because it only expects an ``Element of n`, not
``Text of string`, which a text node is.

In any case, :has() doesn't select text nodes. So,
excluding them beforehand is the way to go.

src/soup.ml

@@ -598,6 +598,7 @@ struct
     | Content s -> texts node |> String.concat "" |> has_substring s
     | Has selector ->
       descendants node
+      |> filter (fun descendant -> not (is_text descendant))
       |> filter (fun descendant -> matches_simple_selector descendant selector)
       |> count
       |> fun count -> count > 0

test/test.ml

@@ -127,6 +127,8 @@ let suites = [
       test "ol:has([id=one])" 0;
       test "li:has([id=one])" 0;
       test ":has(.odd)" 4;
+      test ":has(ul)" 2;
+      test ":has(caption)" 0;
       test
         ("html:root > body.lists[class~=lists] > ul > li#one:nth-child(1) " ^
          "+ li#two")