Fix ftfy name error in Wan pipeline (#12314)

Signed-off-by: Daniel Socek <daniel.socek@intel.com>
Co-authored-by: YiYi Xu <yixu310@gmail.com>

Author: dsocek

src/diffusers/pipelines/wan/pipeline_wan.py

@@ -76,7 +76,8 @@
 
 
 def basic_clean(text):
-    text = ftfy.fix_text(text)
+    if is_ftfy_available():
+        text = ftfy.fix_text(text)
     text = html.unescape(html.unescape(text))
     return text.strip()