Fix desuffixing for crossproduct affixes

This fixes lookup for words like "returns" that are defined by both a
prefix ("re") and a suffix ("s"). Previously the affix was mistakenly
formed with the text rather than the stem, so the stem was "return"
when it should've been "turn."

src/checker.rs

@@ -337,7 +337,9 @@ impl<'a> Checker<'a> {
                 if suffix_allowed
                     && is_some_and(form.prefixes[0].as_ref(), |prefix| prefix.crossproduct)
                 {
-                    for form2 in self.desuffix(word, suffix_flags, forbidden_flags, false, true) {
+                    for form2 in
+                        self.desuffix(&form.stem, suffix_flags, forbidden_flags, false, true)
+                    {
                         forms.push(AffixForm {
                             text: form.text.clone(),
                             prefixes: form.prefixes.clone(),