Merge branch 'pl' into 'develop'

Add Polish translation

Closes #166

See merge request funkwhale/funkwhale!304

changes/changelog.d/polish.i18n

+Polish translation (!304)

front/src/locales.js

@@ -12,6 +12,10 @@ export default {
     {
       "code": "fr_FR",
       "label": "Français"
+    },
+    {
+      "code": "pl",
+      "label": "Polszczyzna"
     }
   ]
 }