Fixed a typo

app/src/main/java/de/kuschku/util/irc/format/IrcFormatDeserializer.java

@@ -110,7 +110,7 @@ public class IrcFormatDeserializer {
      * @param str mIRC formatted String
      * @return a CharSequence with Android’s span format representing the input string
      */
-    @NonNUll
+    @NonNull
     public CharSequence formatString(@Nullable String str) {
         if (str == null) return "";