patch 8.2.4141: Vim9 builtin functions test fails

Problem:    Vim9 builtin functions test fails.
Solution:   Add "scriptversion" item to maparg() result.
diff --git a/src/testdir/test_vim9_builtin.vim b/src/testdir/test_vim9_builtin.vim
index eb86a03..3747a4e 100644
--- a/src/testdir/test_vim9_builtin.vim
+++ b/src/testdir/test_vim9_builtin.vim
@@ -2278,6 +2278,7 @@
         nowait: 0,
         expr: 0,
         sid: SID(),
+        scriptversion: 999999,
         rhs: 'bar',
         buffer: 0})
   unmap foo