minor fix (greek omega used has no diacritic) (#5464)

replaced \u03C9 (GREEK SMALL LETTER OMEGA: ω)
with \u03CE (GREEK SMALL LETTER OMEGA WITH TONOS: ώ)

src/js/select2/diacritics.js

@@ -841,7 +841,7 @@ define([
     '\u03CD': '\u03C5',
     '\u03CB': '\u03C5',
     '\u03B0': '\u03C5',
-    '\u03C9': '\u03C9',
+    '\u03CE': '\u03C9',
     '\u03C2': '\u03C3',
     '\u2019': '\''
   };