Fix #238 Remove all other attrs when mix content attr is present

Notes:
That's my worst case solution... I want to resolve this in
the xml nodes but that seems tricky

xsdata/codegen/handlers/attribute_mismatch.py

@@ -32,3 +32,10 @@ def process(cls, target: Class):
         enumerations = [attr for attr in target.attrs if attr.is_enumeration]
         if len(enumerations) > 0:
             target.attrs = enumerations
+
+        mixed_content = next((attr for attr in target.attrs if attr.mixed), None)
+        if mixed_content:
+            target.attrs.clear()
+            target.attrs.append(mixed_content)
+
+            target.inner.clear()