[i18n] Add polish (pl) translation

CHANGELOG.md

@@ -11,6 +11,8 @@
 - Add custom videoconference system.
 - Add support for comments in the Gitlab webhooks integration.
 - Now profile timelines only show content about the objects (US/Tasks/Issues/Wiki pages) you are involved.
+- i18n.
+  - Add polish (pl) translation.
 
 ### Misc
 - API: Mixin fields 'users', 'members' and 'memberships' in ProjectDetailSerializer

settings/common.py

@@ -126,7 +126,7 @@ LANGUAGES = [
     #("nn", "Norsk (nynorsk)"),  # Norwegian Nynorsk
     #("os", "Ирон æвзаг"),  # Ossetic
     #("pa", "ਪੰਜਾਬੀ"),  # Punjabi
-    #("pl", "Polski"),  # Polish
+    ("pl", "Polski"),  # Polish
     #("pt", "Português (Portugal)"),  # Portuguese
     #("pt-br", "Português (Brasil)"),  # Brazilian Portuguese
     #("ro", "Română"),  # Romanian