Add 'target' attribute to the Bleach allowed attributes (#911) (#912)

Co-authored-by: wlorenzetti <lorenzett@gis3w.it>
(cherry picked from commit 452edb9)

Co-authored-by: Walter Lorenzetti <lorenzetti@gis3w.it>

g3w-admin/base/settings/base.py

@@ -359,7 +359,7 @@
 BLEACH_ALLOWED_TAGS = ['p', 'b', 'i', 'u', 'em', 'strong', 'a', 'br', 'table', 'tr', 'td', 'th', 'b', 'ul', 'li', 'ol',
                        'div', 'h1', 'h2', 'h3', 'h4', 'h5', 'pre', 'blockquote', 'tbody', 'theader', 'tfooter', 'span']
 BLEACH_STRIP_TAGS = True
-BLEACH_ALLOWED_ATTRIBUTES = ['href', 'title', 'style', 'src']
+BLEACH_ALLOWED_ATTRIBUTES = ['href', 'title', 'style', 'src', 'target']
 BLEACH_ALLOWED_STYLES = [
     'background-color', 'color', 'font-size'
 ]