remove python2 warning

Author: adamcrymble

es/lecciones/manipular-cadenas-de-caracteres-en-python.md

@@ -23,7 +23,7 @@ next: de-html-a-lista-de-palabras-1
 previous: trabajar-con-paginas-web
 original: manipulating-strings-in-python
 redirect_from: /es/lessons/manipulating-strings-in-python
-python_warning: true
+python_warning: false
 difficulty: 2
 activity: transforming
 topics: [python]