Update settings_keys.xml

Changed the Somali language name from Af-Soomaali to Soomaali which is common and more user friendly when users are looking for Somali language in the list (since they aren't expecting it starts with A as in Af-Soomaali).
I contributed the language to the project on Weblate and I think this is name is better.

app/src/main/res/values/settings_keys.xml

@@ -1145,7 +1145,7 @@
         <item>sardu</item>
         <item>Slovenčina</item>
         <item>Slovenščina</item>
-        <item>Af Soomaali</item>
+        <item>Soomaali</item>
         <item>Shqip</item>
         <item>Српски</item>
         <item>Svenska</item>