patch 8.2.1429: Vim9: no error for missing white after : in dict

Problem:    Vim9: no error for missing white after : in dict.
Solution:   Check for white space. (closes #6671)  Also check that there is no
            white before the :.
diff --git a/src/testdir/test_vim9_func.vim b/src/testdir/test_vim9_func.vim
index 24078f5..1f9768f 100644
--- a/src/testdir/test_vim9_func.vim
+++ b/src/testdir/test_vim9_func.vim
@@ -774,7 +774,7 @@
     enddef
 
     def RetListAny(): list<any>
-      return items({'k' : 'v'})
+      return items({'k': 'v'})
     enddef
 
     def RetListString(): list<string>